Partenaires

Nos tutelles

Centre National de la Recherche Scientifique Université de Caen ENSICAEN Normandie Université

LPC CAEN
ENSICAEN
6, bd du Maréchal Juin
14050 CAEN Cedex
Tel : +033 (0) 231452500



Annuaire


Organigrammes


Contacts

Rechercher





Accueil > Recherche & Enseignement

M. Nigel Orr


Chercheur CNRS


Groupe : Structure nucléaire


orr lpccaen.in2p3.fr


Tél : +33 2 31 45 29 72



PUBLICATIONS

[hal-01642315] Elastic scattering of $^{8}$He + $^{4}$He and two-neutron transfer and the influence of resonances in $^{12}$Be

22 novembre 2017

Scattering of 8 He from 4 He has been performed through the coincident detection of the scattered particles using a silicon array within a helium-4 gas volume with a 8 He beam. This permitted the reconstruction of the interaction probability as a function of position within the gas and hence (...)

Lire la suite

[hal-01642930] Low-lying neutron $fp$-shell intruder states in $^{27}Ne$

22 novembre 2017

The quenching of the N=20 shell gap in neutron-rich nuclei is investigated by studying the single-particle structure of 27Ne via neutron transfer using a 26Ne beam. Two low-lying negative-parity intruder states have been observed, the lowest of which is identified as Jπ=3/2−, confirming earlier (...)

Lire la suite

[hal-01642850] Spectroscopy of $^{39,41}$Si and the border of the N $=$ 28 island of inversion

22 novembre 2017

The structure of the very neutron-rich nuclei ^3^9Si and ^4^1Si has been investigated via in-beam @c-ray spectroscopy and few-nucleon knockout from radioactive beams. The observation of low-lying states in ^3^9Si is a clear evidence for a drastic lowering of the intruder neutron 3/2^- state (...)

Lire la suite

[hal-01642974] One-neutron removal from $^{29}Ne$ : Defining the lower limits of the island of inversion

22 novembre 2017

Background: Very neutron-rich isotopes, including Ne30−32, in the vicinity of N=20 are known to exhibit ground states dominated by fp-shell intruder configurations: the “island of inversion.” Systematics for the Ne-isotopic chain suggest that such configurations may be in strong competition with (...)

Lire la suite

[hal-01642929] Resonances in $C^{11}$ observed in the $He^{4}$($Be^{7},\alpha$)$Be^{7}$ and $He^{4}$($Be^{7},\rho$)$B^{10}$ reactions

22 novembre 2017

Measurements of the 4He(7Be,α)7Be and 4He(7Be,p)10B reactions were performed using 7Be beam energies of 7.1 and 23 MeV and a helium-4 target, employing the thick target technique. Resonances were observed between Ex(11C)=8.6 to 13.8 MeV. An R-matrix analysis was performed to characterize the (...)

Lire la suite

[hal-01641837] Interaction cross section study of the two-neutron halo nucleus $^{22}C$

21 novembre 2017

The interaction cross sections ( σI ) of the very neutron-rich carbon isotopes 19 C, 20 C and 22 C have been measured on a carbon target at 307, 280, and 235 MeV/nucleon, respectively. A σI of 1.280±0.023 b was obtained for 22 C, significantly larger than for 19,20 C, supporting the halo character (...)

Lire la suite

[hal-01641054] Spectroscopy of $^{39,41}$Si and the border of the N $=$ 28 island of inversion

21 novembre 2017

The structure of the very neutron-rich nuclei ^3^9Si and ^4^1Si has been investigated via in-beam @c-ray spectroscopy and few-nucleon knockout from radioactive beams. The observation of low-lying states in ^3^9Si is a clear evidence for a drastic lowering of the intruder neutron 3/2^- state (...)

Lire la suite

[hal-01641134] Low-lying neutron $fp$-shell intruder states in $^{27}Ne$

21 novembre 2017

The quenching of the N=20 shell gap in neutron-rich nuclei is investigated by studying the single-particle structure of 27Ne via neutron transfer using a 26Ne beam. Two low-lying negative-parity intruder states have been observed, the lowest of which is identified as Jπ=3/2−, confirming earlier (...)

Lire la suite

[hal-01641456] Spectroscopy of $He^{7}$ using the $Be^{9}$($He^{6}$,$Be^{8}$) transfer reaction

21 novembre 2017

The unbound nucleus He7 has been investigated via the reaction of a 16.8 MeV He6 radioactive ion beam on a Be9 target. The measurement of the outgoing Be8 through its well characterized two-α decay permitted the energy of the He6+n system to be reconstructed. Through comparison with a complete (...)

Lire la suite

[hal-01641178] One-neutron removal from $^{29}Ne$ : Defining the lower limits of the island of inversion

21 novembre 2017

Background: Very neutron-rich isotopes, including Ne30−32, in the vicinity of N=20 are known to exhibit ground states dominated by fp-shell intruder configurations: the “island of inversion.” Systematics for the Ne-isotopic chain suggest that such configurations may be in strong competition with (...)

Lire la suite

[hal-01641957] Experimental study of high-lying states in $^{28}$Mg using the resonant elastic scattering of $\alpha$ particles

21 novembre 2017

The excitation function of $^28$Mg above the α-decay threshold has been measured for the first time using the resonant scattering of α particles with the technique of a thick target in inverse kinematics. Thirteen new states are reported between E$_x$=15.5 and E$_x$=20.5 MeV, and suggestions for (...)

Lire la suite

[hal-01641133] Resonances in $C^{11}$ observed in the $He^{4}$($Be^{7},\alpha$)$Be^{7}$ and $He^{4}$($Be^{7},\rho$)$B^{10}$ reactions

21 novembre 2017

Measurements of the 4He(7Be,α)7Be and 4He(7Be,p)10B reactions were performed using 7Be beam energies of 7.1 and 23 MeV and a helium-4 target, employing the thick target technique. Resonances were observed between Ex(11C)=8.6 to 13.8 MeV. An R-matrix analysis was performed to characterize the (...)

Lire la suite

[hal-01554621] Single-neutron knockout from $^{20}\textrm{C}$ and the structure of $^{19}\textrm{C}$

5 juillet 2017

The low-lying unbound level structure of the halo nucleus 19 C has been investigated using single-neutron knockout from 20 C on a carbon target at 280 MeV/nucleon. The invariant mass spectrum, derived from the momenta of the forward going beam velocity 18 C fragment and neutrons, was found to (...)

Lire la suite

[in2p3-01359046] Spectroscopy of He$^{7}$ using the Be$^{9}$(He$^{6}$,Be$^{8}$) transfer reaction

18 février 2017

The unbound nucleus He7 has been investigated via the reaction of a 16.8 MeV He6 radioactive ion beam on a Be9 target. The measurement of the outgoing Be8 through its well characterized two-α decay permitted the energy of the He6+n system to be reconstructed. Through comparison with a complete (...)

Lire la suite

[in2p3-01394089] Experimental study of high-lying states in $^{28}$Mg using the resonant elastic scattering of α particles

8 novembre 2016

The excitation function of Mg28 above the α-decay threshold has been measured for the first time using the resonant scattering of α particles with the technique of a thick target in inverse kinematics. Thirteen new states are reported between Ex=15.5 and Ex=20.5 MeV, and suggestions for (...)

Lire la suite

[in2p3-01367797] Interaction cross section study of the two-neutron halo nucleus $^{22}$C

16 septembre 2016

The interaction cross sections (σI) of the very neutron-rich carbon isotopes 19C, 20C and 22C have been measured on a carbon target at 307, 280, and 235MeV/nucleon, respectively. A σIof 1.280 ±0.023bwas obtained for 22C, significantly larger than for 19,20C, supporting the halo character of 22C. A (...)

Lire la suite

[in2p3-01326382] Shell evolution approaching the N=20 island of inversion: Structure of 26Na

3 juin 2016

The levels in 26Na with single particle character have been observed for the first time using the d(25Na, pγ ) reaction at 5 MeV/nucleon. The measured excitation energies and the deduced spectroscopic factors are in good overall agreement with (0+1)ħω shell model calculations performed in a (...)

Lire la suite

[in2p3-01285922] Nucleus $^{26}$O: A Barely Unbound System beyond the Drip Line

10 mars 2016

The unbound nucleus 26O has been investigated using invariant-mass spectroscopy following one-proton removal reaction from a 27F beam at 201 MeV/nucleon. The decay products, 24O and two neutrons, were detected in coincidence using the newly commissioned SAMURAI spectrometer at the RIKEN (...)

Lire la suite

[in2p3-01266090] One-neutron removal from Ne29: Defining the lower limits of the island of inversion

3 février 2016

Background: Very neutron-rich isotopes, including Ne30−32, in the vicinity of N=20 are known to exhibit ground states dominated by fp-shell intruder configurations: the “island of inversion.” Systematics for the Ne-isotopic chain suggest that such configurations may be in strong competition with (...)

Lire la suite

[in2p3-01244201] Structure of $^{26}$Na via a Novel Technique Using ($d,p\gamma $) with a Radioactive $^{25}$Na Beam

16 décembre 2015

States in 26Na were populated in the (d, pγ) reaction, induced by bombarding deuterium target nuclei with an intense reaccelerated beam of 25Na ions from the ISAC2 accelerator at TRIUMF. Gamma-rays were recorded in coincidence with protons and used to extract differential cross sections for 21 (...)

Lire la suite

[in2p3-00259696] Single-Proton Removal Reaction Study of $^{16}$B

3 juillet 2015

The low-lying level structure of the unbound system $^16$B has been investigated via single-proton removal from a 35 MeV/nucleon $^17$C beam. The coincident detection of the beam velocity $^15$B fragment and neutron allowed the relative energy of the in-flight decay of $^16$B to be (...)

Lire la suite

[in2p3-00202877] Evidence for core excitation in single-particle states of $^{19}$Na

3 juillet 2015

We present an experimental study of $^19$Na states in the excitation energy range between 2 and 3 MeV. The presence of $^19$Na single-particle levels at these energies was first predicted by a microscopic cluster model and then experimentally confirmed by measuring the elastic and inelastic (...)

Lire la suite

[in2p3-00149418] B(E1) Strengths from Coulomb Excitation of $^{11}$Be

3 juillet 2015

The $B$(E1;$1/2^+\to1/2^-$) strength for $^11$Be has been extracted from intermediate energy Coulomb excitation measurements, over a range of beam energies using a new reaction model, the extended continuum discretized coupled channels (XCDCC) method. In addition, a measurement of the (...)

Lire la suite

[in2p3-00025637] Structure of $^{12}$Be : intruder d-wave strength at N=8

3 juillet 2015

The breaking of the N=8 shell-model magic number in the $^12$Be ground state has been determined to include significant occupancy of the intruder d-wave orbital. This is in marked contrast with all other N=8 isotones, both more and less exotic than $^12$Be. The occupancies of the 0hw vp$_1/2$ (...)

Lire la suite

[in2p3-01090228] Neutron occupancy of the 0d5/2 orbital and the N = 16 shell closure in 24O

3 juillet 2015

One-neutron knockout from 24O leading to the first excited state in 23O has been measured for a proton target at a beam energy of 62 MeV/nucleon. The decay energy spectrum of the neutron unbound state of 23O was reconstructed from the measured four momenta of the 22O fragment and emitted (...)

Lire la suite

[in2p3-00113831] $^{8}$Be + $^{14}$C break-up of $^{22}$Ne

3 juillet 2015

The $^12$C($^18$O, $^14$C + $^8$Be)$^8$Be reaction was studied at a beam energy of 140 MeV. Two multi-element charged-particle telescopes were used to detect the decay of $^22$Ne states into $^14$C + $^8$Be. The reconstructed excitation energy spectrum indicates that two states at 24.14(20) and (...)

Lire la suite

[in2p3-00189364] Virtual coupling potential for elastic scattering of $^{10,11}$Be on proton and carbon targets

3 juillet 2015

The 10;11Be(p,p) and (12C, 12C) reactions were analyzed to determine the in uence of the weak binding energies of exotic nuclei on their interaction potential. The elastic cross sections were measured at GANIL in inverse kinematics using radioactive 10;11Be beams produced at energies of 39:1 A (...)

Lire la suite

[in2p3-00089852] $\beta$-decay studies of neutron-rich K isotopes

3 juillet 2015

The beta decay of the neutron-rich nuclei $^51-53$K has been used to populate bound and unbound states in $^50-53$Ca. Measurements of gamma rays as well as beta-delayed neutrons enabled detailed decay schemes to be established and levels identified in $^50-53$Ca. A delayed one-neutron emission (...)

Lire la suite

[in2p3-00144999] Mass measurements of neutron-rich nuclei near the N=20 and 28 shell closures

3 juillet 2015

Mass measurements of very neutron-rich nuclei near the N=20 and 28 shell closures are presented. Seven masses have been determined for the first time and the precision of 36 masses has been significantly improved. These results are used to investigate the evolution of the odd–even staggering of (...)

Lire la suite

[in2p3-00145207] Collapse of the N=28 shell closure in $^{42}$Si

3 juillet 2015

The energies of the excited states in very neutron-rich $^42$Si and $^41,43$P have been measured using in-beam$gamma$-ray spectroscopy from the fragmentation of secondary beams of $^42,44$S at 39 A.MeV. The low $2^+ $ energy of $^42$Si, 770(19) keV, together with the level schemes of $^41,43$P (...)

Lire la suite

[in2p3-00131478] $\alpha$ decay of excited states in $^{14}$C

3 juillet 2015

Measurements of the $^14$C($^14$C,$^14$C[$^10$Be + α]) breakup reaction have been made at a beam energy of 98.2 MeV. The studies were performed with two charged-particle telescopes that permitted the energy, mass, charge, and emission angle of each detected particle to be determined. A series of (...)

Lire la suite

[in2p3-00025564] High-energy two-neutron removal from $^{10}$Be

3 juillet 2015

A kinetically complete measurement of the $^12$C($^10$Be, alpha+alpha+n) and ($^10$Be, alpha+alpha) reactions has been performed at a beam energy of 30 MeV/nucleon. The charged beam velocity particles were detected in an array of Si-CsI detectors placed at zero degrees, and the neutrons in an (...)

Lire la suite

[in2p3-00025562] $\alpha:2n:\alpha$ molecular band in $^{10}$Be

3 juillet 2015

The 10.15 MeV resonance in $^10$Be has been probed via resonant $^6$He+$^4$He elastic scattering. It is demonstrated that it is the J$^p$i=4$^+$ member of a rotational band built on the 6.18 MeV 0$^+ $state. A Gammaalpha of 0.10–0.13 MeV and Gammaalpha/Gamma=0.35–0.46 were deduced. The (...)

Lire la suite

[in2p3-01044774] N=16 Spherical Shell Closure in O-24

3 juillet 2015

The unbound excited states of the neutron drip-line isotope O-24 have been investigated via the O-24(p, p')O-23 + n reaction in inverse kinematics at a beam energy of 62 MeV/nucleon. The decay energy spectrum of O-24* was reconstructed from the momenta of O-23 and the neutron. The spin parity (...)

Lire la suite

[in2p3-00024152] Study of $^{19} $Na at SPIRAL

3 juillet 2015

The excitation function for the elastic-scattering reaction p18Ne, p18Ne was measured with the first radioactive beam from the SPIRAL facility at the GANIL laboratory and with a solid cryogenic hydrogen target. Several broad resonances have been observed, corresponding to new excited states in (...)

Lire la suite

[in2p3-00024673] The $^7Be(d,p)2\alpha$ cross section at Big Bang energies and the primordial $^7$Li abundance

1er juillet 2015

The WMAP satellite, devoted to the observations of the anisotropies of the Cosmic Microwave Background (CMB) radiation, has recently provided a determination of the baryonic density of the Universe with unprecedented precision. Using this, Big Bang Nucleosynthesis (BBN) calculations predict a (...)

Lire la suite

[in2p3-00238356] Breakup reaction study of the Brunnian nucleus $^{10}$C

1er juillet 2015

The structure and 2α + 2p breakup of $^10$C, the only known Brunnian nucleus, has been studied at 33.3 MeV/nucleon. The breakup kinematics were used to reconstruct the $^10$C→$^9$B +p, $^9$B→$^8$Be +p, $^8$Be→ α + α and $^10$C → $^6$Be +α, $^6$Be → $^5$Li +p, $^5$Li → α + p decay paths. Proton emission (...)

Lire la suite

[in2p3-00024861] Mass measurements with the CIME cyclotron at GANIL

1er juillet 2015

A new direct technique using the CIME cyclotron as a high-resolution mass spectrometer is being developed in order to measure the masses of exotic nuclei. Tests have been performed to check the feasibility of the method with a mixed beam of stable ions extracted from the SPIRAL ion source and (...)

Lire la suite

[in2p3-00071159] alpha-decaying states $^{18}$O, $^{20}$Ne and $^{22}$Ne in $^{18}$O beam induced reactions

1er juillet 2015

The three reactions $^12$C($^18$O,$^14$C + α)$^12$C, $^12$C($^18$O,$^16$O + α)$^10$Be, and $^12$C($^18$O,$^18$O + α)$^8$Be have been used to investigate α-decaying states in the nuclei $^18$O, $^20$Ne, and $^22$Ne populated through inelastic scattering, 2p, and α transfer, respectively. The (...)

Lire la suite

[in2p3-00112871] Reaction cross-section and reduced strong absorption radius measurements of neutron-rich nuclei in the vicinity of closed shells N=20 and N=28

1er juillet 2015

The energy-integrated reaction cross-sections of several neutron-rich nuclei (17−22N, 19−24O, 21−27F, 23−30Ne, 26−33Na, 28−35Mg, 31−38Al, 33−40Si, 36−42P, 39−44S, 42−45Cl, 45,46Ar), measured at intermediate energy (30–65 A MeV), via direct method, are presented. Silicon detectors have been used as the (...)

Lire la suite

[in2p3-01027507] Observation of a p-wave one-neutron halo configuration in 37Mg

20 mai 2015

Cross sections of 1n-removal reactions from the neutron-rich nucleus Mg37 on C and Pb targets and the parallel momentum distributions of the Mg37 residues from the C target have been measured at 240 MeV/nucleon. A combined analysis of these distinct nuclear- and Coulomb-dominated reaction data (...)

Lire la suite

[in2p3-00303355] Direct mass measurements of $^{68}$Se and $^{80}$Y

20 mai 2015

The masses of neutron-deficient nuclides near the N=Z line with A=64-80 have been determined using a direct time-of-flight technique which employed a cyclotron as a high-resolution spectrometer. The measured atomic masses for $^68$Se and $^80$Y were 67.9421(3) u and 79.9344(2) u, respectively. (...)

Lire la suite

Neutron occupancy of 0d5/2 orbital in 24O

2 juillet 2014

The partial one-neutron removal cross section of 24O leading to the first excited state in 23O has been measured to be 65.7 ± 5.3 mb with a proton target in inverse kinematics at the beam energy of 62 MeV/nucleon. The decay energy spectrum of the neutron unbound state of 23O was reconstructed (...)

Lire la suite

[in2p3-00977048] Deformation-Driven p-Wave Halos at the Drip Line: 31Ne

10 avril 2014

The halo structure of Ne31 is studied using 1n-removal reactions on C and Pb targets at 230 MeV/nucleon. A combined analysis of the cross sections of these nuclear and Coulomb dominated reactions that feed directly the Ne30 ground-state reveals Ne31 to have a small neutron separation energy, (...)

Lire la suite

Structure of 13Be probed via secondary-beam reactions

27 mars 2014

The low-lying level structure of the unbound neutron-rich nucleus 13Be has been investigated via breakup on a carbon target of secondary beams of 14,15B at 35 MeV/nucleon. The coincident detection of the beam velocity 12Be fragments and neutrons permitted the invariant mass of the 12Be+n and (...)

Lire la suite

[in2p3-00943130] Two-neutron transfer reaction mechanisms in 12C(6He,4He)14C using a realistic three-body 6He model

7 février 2014

The reaction mechanisms of the two-neutron transfer reaction 12C(6He,4He) have been studied at Elab=30 MeV at the TRIUMF ISAC-II facility using the Silicon Highly-segmented Array for Reactions and Coulex (SHARC) charged-particle detector array. Optical potential parameters have been extracted (...)

Lire la suite

[in2p3-00920222] Structure of $^{13}$Be probed via secondary beam reactions

18 décembre 2013

The low-lying level structure of the unbound neutron-rich nucleus $^13$Be has been investigated via breakup on a carbon target of secondary beams of $^14,15$B at 35 MeV/nucleon. The coincident detection of the beam velocity $^12$Be fragments and neutrons permitted the invariant mass of the (...)

Lire la suite

[in2p3-00858297] Structure of unbound neutron-rich $^{9}$He studied using single-neutron transfer

5 septembre 2013

The 8He(d,p) reaction was studied in inverse kinematics at 15.4A MeV using the MUST2 Si-CsI array in order to shed light on the level structure of 9He. The well known 16O(d,p)17O reaction, performed here in reverse kinematics, was used as a test to validate the experimental methods. The 9He (...)

Lire la suite

[in2p3-00846623] Publisher's Note: In-beam spectroscopic studies of the 44S nucleus [Phys. Rev. C 85, 024311 (2012)]

19 juillet 2013

This paper was published online on 15 February 2012 with errors in Figs. 2 and 4. The figures has been replaced as of 28 February 2012. The figures are correct in the printed version of the journal.

Lire la suite

Breakup Reactions of Drip-Line Nuclei Near N = 20, 28

16 mai 2013

The one-neutron removal cross section from 29Ne, 33,35,37Mg, and 39,41Si on a Pb target have been measured at around 240 MeV/nucleon at the RIBF (RI-Beam Factory) at RIKEN. This main goal of the experiment was to extract the inclusive Coulomb breakup cross sections in order to probe possible (...)

Lire la suite

Invariant Mass Spectroscopy of O-23 via the (p, p') Reaction in Inverse Kinematics

16 mai 2013

The neutron-rich oxygen isotope O-23 has been investigated via proton inelastic scattering on a liquid hydrogen target at 63.5 MeV/nucleon. The invariant mass method in inverse kinematics was employed to reconstruct the energy spectrum. A sharp resonance state was observed at 42(5) keV above (...)

Lire la suite

The N=16 Spherical Shell Closure in O-24

16 mai 2013

The unbound excited states of the most neutron-rich dripline oxygen isotope, O-24, have been investigated by using the O-24(p,p')O-24(*) reaction at the beam energy of 62 MeV/nucleon in inverse kinematics. The first and second unbound excited states of O-24 have been observed at MeV and MeV (...)

Lire la suite

The N = 16 spherical shell closure in 24O

6 février 2013

The unbound excited states of the neutron drip-line isotope 24O have been investigated via the 24O(p,p')23O+n reaction in inverse kinematics at a beam energy of 62 MeV/nucleon. The decay energy spectrum of 24O* was reconstructed from the momenta of 23O and the neutron. The spin-parity of the (...)

Lire la suite

[in2p3-00785471] Comment on "First Observation of Ground State Dineutron Decay: 16Be

6 février 2013

A recent measurement [Spyrou et al., PRL 108, 102501 (2012)] of the in-flight decay of 16Be into 14Be+n+n has been interpreted as the first case of dineutron emission. Here we point out that the inclusion of the n-n interaction neglected in the description of the direct three-body decay can (...)

Lire la suite

[in2p3-00752211] Direct mass measurements of 19B, 22C, 29F, 31Ne, 34Na and other light exotic nuclei

15 novembre 2012

We report on direct time-of-flight based mass measurements of 16 light neutron-rich nuclei. These include the first determination of the masses of the Borromean drip-line nuclei $^19$B, $^22$C and $^29$F as well as that of $^34$Na. In addition, the most precise determinations to date for $^23$N (...)

Lire la suite

Neutron and charged particle identification by means of various detectors

11 septembre 2012

Identification methods for photons, neutrons and heavy ions by using scintillator and semiconductor detectors are discussed by stressing the advantages of signal digitization.

Lire la suite

[in2p3-00719389] One-proton breakup of 24Si and the 23Al( p, γ )24Si reaction in type I x-ray bursts

19 juillet 2012

To understand explosive hydrogen burning in stars and to explore various explosive scenarios such as type I x-ray bursts (XRBs), reliable reaction rates are needed. The cross sections for radiative proton capture on near-dripline nuclei are necessary for the determination of the reaction rates, (...)

Lire la suite

The first 2 + excited state of 24O

27 avril 2012

The unbound excited states of the most neutron-rich dripline oxygen isotope, O (Z=8, N=16), have been investigated using the 24O(p, p′)O* reaction at the beam energy of 63 MeV/nucleon in inverse kinematics at RIKEN. The 24O beam was produced in the projectile-like fragmentation process of a 95 (...)

Lire la suite

Invariant Mass Spectroscopy of 23O via the (p, p′) Reaction in Inverse Kinematics

27 avril 2012

The neutron-rich oxygen isotope 23O has been investigated via proton inelastic scattering on a liquid hydrogen target at 63.5 MeV/nucleon. The invariant mass method in inverse kinematics was employed to reconstruct the energy spectrum. A sharp resonance state was observed at 42(5) keV above the (...)

Lire la suite

The N = 16 Spherical Shell Closure in 24O

27 avril 2012

The unbound excited states of the most neutron-rich dripline oxygen isotope, 24O, have been investigated by using the 24O(p, p′) 24O * reaction at the beam energy of 62 MeV/nucleon in inverse kinematics. The first and second unbound excited states of 24O have been observed at Mathematical (...)

Lire la suite

Direct radiative proton capture 23Al(p,$\alpha$)24Si studied via one-proton nuclear breakup of 24Si

1er mars 2012

We present the results of an experimental work that studied the direct component of the radiative proton capture reaction 23Al(p,$\gamma$)24Si for its relevance in X-ray burst nucleosynthesis. The experiment was performed at GANIL using one-proton nuclear breakup reaction at intermediate (...)

Lire la suite

Spectroscopy of 22,23,24Si and 22Al

17 février 2012

β-delayed one- and two-proton and α spectroscopic studies of the neutron-deficient nuclei 22,23,24Si and 22Al produced in projectile fragmentation of a 36Ar primary beam at 95 MeV/u have been performed at GANIL. Isotopes of interest were analyzed using the LISE3 spectrometer and were implanted in (...)

Lire la suite

Evidence Of A (1)2 Component To The 12Be Ground State

17 février 2012

Data have been obtained on exclusive single neutron knockout cross sections from 12Be to study its ground state structure. The cross sections for the production of 11Be in its ground state (1/2+) and first excited state (0.32 MeV, 1/2−) have previously been measured, indicating a strong (2s½)2 (...)

Lire la suite

Low-energy F18(p, α)O15 cross section measurements relevant to nova γ-ray emission

16 février 2012

During nova outbursts the decay of F18 is the main source of γ-ray emission at and below 511 keV. In spite of much experimental effort, the quantity of F18 synthesized still suffers from large uncertainties which arise mainly from the F18(p, α)O15 reaction cross section at low energies. We report (...)

Lire la suite

[in2p3-00662400] Low-lying neutron f p-shell intruder states in 27Ne

24 janvier 2012

The quenching of the N = 20 shell gap in neutron-rich nuclei is investigated by studying the single-particle structure of 27Ne via neutron transfer using a 26Ne beam. Two low-lying negative-parity intruder states have been observed, the lowest of which is identified as J π = 3/2−, confirming (...)

Lire la suite

One and two neutron removal reactions from the most neutron-rich carbon isotopes

10 janvier 2012

The structure of $^19,20,22$C has been investigated using high-energy (about 240 MeV/nucleon) one- and two-neutron removal reactions on a carbon target. Measurements were made of the inclusive cross sections and momentum distributions for the charged residues. Narrow momentum distributions were (...)

Lire la suite

[in2p3-00658293] One and two neutron removal reactions from the most neutron-rich carbon isotopes

10 janvier 2012

The structure of $^19,20,22$C has been investigated using high-energy (about 240 MeV/nucleon) one- and two-neutron removal reactions on a carbon target. Measurements were made of the inclusive cross sections and momentum distributions for the charged residues. Narrow momentum distributions were (...)

Lire la suite

Resonances in 11C observed in the 4He(7Be,α)7Be and 4He(7Be,p)10B reactions

10 janvier 2012

Measurements of the 4He(7Be,α)7Be and 4He(7Be,p)10B reactions were performed using 7Be beam energies of 7.1 and 23 MeV and a helium-4 target, employing the thick target technique. Resonances were observed between Ex(11C)=8.6 to 13.8 MeV. An R-matrix analysis was performed to characterize the (...)

Lire la suite

[in2p3-00658279] Resonances in 11C observed in the 4He(7Be,α)7Be and 4He(7Be,p)10B reactions

10 janvier 2012

Measurements of the 4He(7Be,α)7Be and 4He(7Be,p)10B reactions were performed using 7Be beam energies of 7.1 and 23 MeV and a helium-4 target, employing the thick target technique. Resonances were observed between Ex(11C)=8.6 to 13.8 MeV. An R-matrix analysis was performed to characterize the (...)

Lire la suite

[in2p3-00657202] In-beam spectroscopic studies of $^{44}$S nucleus

6 janvier 2012

The structure of the $^44$S nucleus has been studied at GANIL through the one proton knock-out reaction from a $^45$Cl secondary beam at 42~A$\cdot$MeV. The $\gamma$ rays following the de-excitation of $^44$S were detected in flight using the 70 BaF$_2$ detectors of the Ch\^ateau de Cristal (...)

Lire la suite

SHARC: Silicon Highly-segmented Array for Reactions and Coulex used in conjunction with the TIGRESS gamma-ray spectrometer

17 novembre 2011

The combination of gamma-ray spectroscopy and charged-particle spectroscopy is a powerful tool for the study of nuclear reactions with beams of nuclei far from stability. This paper presents a new silicon detector array, SHARC, the Silicon Highly-segmented Array for Reactions and Coulex. The (...)

Lire la suite

[in2p3-00642092] SHARC: Silicon Highly-segmented Array for Reactions and Coulex used in conjunction with the TIGRESS gamma-ray spectrometer

17 novembre 2011

The combination of gamma-ray spectroscopy and charged-particle spectroscopy is a powerful tool for the study of nuclear reactions with beams of nuclei far from stability. This paper presents a new silicon detector array, SHARC, the Silicon Highly-segmented Array for Reactions and Coulex. The (...)

Lire la suite

Measurement of Unbound Excited States of (24)O

17 novembre 2011

The unbound excited states of the most neutron-rich oxygen isotope, (24)O (Z = 8, N = 16), have been investigated using the (24)O(p,p')(24)O*-->(23)O+n reaction at RIKEN, where a 63 MeV/neuclon secondary beam of (24)O was produced in a Be production target by the projectile-like (...)

Lire la suite

[in2p3-00642050] Measurement of Unbound Excited States of (24)O

17 novembre 2011

The unbound excited states of the most neutron-rich oxygen isotope, (24)O (Z = 8, N = 16), have been investigated using the (24)O(p,p')(24)O*-->(23)O+n reaction at RIKEN, where a 63 MeV/neuclon secondary beam of (24)O was produced in a Be production target by the projectile-like (...)

Lire la suite

Invariant Mass Spectroscopy for the Neutron Rich Nuclei

17 novembre 2011

The neutron-rich carbon isotopes (19,17)C and a boron isotope (14)B are investigated respectively via proton inelastic and charge-exchange reactions on a liquid hydrogen target at around 70 MeV/nucleon at RIKEN. The invariant mass method in inverse kinematics involving coincidence detection of (...)

Lire la suite

[in2p3-00642043] Invariant Mass Spectroscopy for the Neutron Rich Nuclei

17 novembre 2011

The neutron-rich carbon isotopes (19,17)C and a boron isotope (14)B are investigated respectively via proton inelastic and charge-exchange reactions on a liquid hydrogen target at around 70 MeV/nucleon at RIKEN. The invariant mass method in inverse kinematics involving coincidence detection of (...)

Lire la suite

Structure of the neutron-rich N = 7 isotones 10Li and 9He

7 novembre 2011

The near threshold structure of the unbound N=7 isotones 10Li and 9He has been investigated using proton removal and breakup from intermediate energy (35 MeV/nucleon) secondary beams of 11Be and 14,15B. The coincident detection of the beam velocity 9Li and 8He fragments and neutrons permitted (...)

Lire la suite

Structure of the neutron-rich N = 7 isotones 10Li and 9He

7 novembre 2011

The near threshold structure of the unbound N=7 isotones 10Li and 9He has been investigated using proton removal and breakup from intermediate energy (35 MeV/nucleon) secondary beams of 11Be and 14,15B. The coincident detection of the beam velocity 9Li and 8He fragments and neutrons permitted (...)

Lire la suite

Spectroscopy of 39,41Si and the border of the N = 28 island of inversion

6 septembre 2011

The structure of the very neutron-rich nuclei 39Si and 41Si has been investigated via in-beam γ -ray spectroscopy and few-nucleon knockout from radioactive beams. The observation of low-lying states in 39Si is a clear evidence for a drastic lowering of the intruder neutron 3/2− state when going (...)

Lire la suite

[in2p3-00619310] Spectroscopy of 39,41Si and the border of the N = 28 island of inversion

6 septembre 2011

The structure of the very neutron-rich nuclei 39Si and 41Si has been investigated via in-beam γ -ray spectroscopy and few-nucleon knockout from radioactive beams. The observation of low-lying states in 39Si is a clear evidence for a drastic lowering of the intruder neutron 3/2− state when going (...)

Lire la suite

Description of current pulses induced by heavy ions in silicon detectors (II)

20 avril 2011

Current pulses induced in a silicon detector by 10 different heavy ion species at known energies around 10 AMeV have been sampled in time at high frequency. Their individual average shapes are quite well reproduced by a fit procedure based on our recent charge carrier collection treatment which (...)

Lire la suite

[in2p3-00587352] Description of current pulses induced by heavy ions in silicon detectors (II)

20 avril 2011

Current pulses induced in a silicon detector by 10 different heavy ion species at known energies around 10 AMeV have been sampled in time at high frequency. Their individual average shapes are quite well reproduced by a fit procedure based on our recent charge carrier collection treatment which (...)

Lire la suite

Structure of 23Al from one-proton breakup reaction and astrophysical implications

6 avril 2011

The ground state of the proton-rich nucleus 23Al has been studied by one-proton removal on a carbon target at about 50 MeV/nucleon using the EXOGAM + SPEG experimental setup at GANIL. Longitudinal momentum distributions of the 22Mg breakup fragments, inclusive and in coincidence with gamma rays (...)

Lire la suite

[in2p3-00583596] Structure of 23Al from one-proton breakup reaction and astrophysical implications

6 avril 2011

The ground state of the proton-rich nucleus 23Al has been studied by one-proton removal on a carbon target at about 50 MeV/nucleon using the EXOGAM + SPEG experimental setup at GANIL. Longitudinal momentum distributions of the 22Mg breakup fragments, inclusive and in coincidence with gamma rays (...)

Lire la suite

Emergence of the N=16 shell gap in $^{21}$O

21 décembre 2010

The spectroscopy of 21O has been investigated using a radioactive 20O beam and the (d,p) reaction in inverse kinematics. The ground and first excited states have been determined to be Jpi=5/2+ and Jpi=1/2+ respectively. Two neutron unbound states were observed at excitation energies of 4.76 +- (...)

Lire la suite

[in2p3-00548964] Emergence of the N=16 shell gap in $^{21}$O

21 décembre 2010

The spectroscopy of 21O has been investigated using a radioactive 20O beam and the (d,p) reaction in inverse kinematics. The ground and first excited states have been determined to be Jpi=5/2+ and Jpi=1/2+ respectively. Two neutron unbound states were observed at excitation energies of 4.76 +- (...)

Lire la suite

Direct measurement of the 18F(p,alpha)15O reaction for application to nova gamma-ray emission

25 novembre 2010

The 18F nucleus is one of the radioactive isotopes produced during nova explosions. It is of particular interest since it is mainly responsible for the 511 keV gamma-ray emission of novae that could be detected with the INTEGRAL satellite or future gamma-ray telescopes. The amount of 18F (...)

Lire la suite

Direct measurement of the 18F(p,alpha)15O reaction for application to nova gamma-ray emission

25 novembre 2010

The 18F nucleus is one of the radioactive isotopes produced during nova explosions. It is of particular interest since it is mainly responsible for the 511 keV gamma-ray emission of novae that could be detected with the INTEGRAL satellite or future gamma-ray telescopes. The amount of 18F (...)

Lire la suite

Shell and shapes in the $^{44}S nucleus

25 octobre 2010

The results obtained from electron and in-beam spectroscopy experiments reveal that the 44S nucleus is located in a transitional region between the spherical 48Ca and the oblate 42Si. The comparison of the results with Large Scale Shell Model calculations points towards prolate-spherical shape (...)

Lire la suite

Shell and shapes in the $^{44}S nucleus

25 octobre 2010

The results obtained from electron and in-beam spectroscopy experiments reveal that the 44S nucleus is located in a transitional region between the spherical 48Ca and the oblate 42Si. The comparison of the results with Large Scale Shell Model calculations points towards prolate-spherical shape (...)

Lire la suite

Structure of the neutron-rich N=7 isotones 10Li and 9He

15 septembre 2010

The near threshold structure of the unbound N=7 isotones 10Li and 9He has been investigated using proton removal and breakup from intermediate energy (35 MeV/nucleon) secondary beams of 11Be and 14,15B. The coincident detection of the beam velocity 9Li and 8He fragments and neutrons permitted (...)

Lire la suite

Structure of the neutron-rich N=7 isotones 10Li and 9He

15 septembre 2010

The near threshold structure of the unbound N=7 isotones 10Li and 9He has been investigated using proton removal and breakup from intermediate energy (35 MeV/nucleon) secondary beams of 11Be and 14,15B. The coincident detection of the beam velocity 9Li and 8He fragments and neutrons permitted (...)

Lire la suite

The β–γ decay of 21Na

12 avril 2010

A new and independent determination of the Gamow–Teller branching ratio in the β-decay of 21Na is reported. The value 5.13 ± 0.43% obtained is in agreement with the currently adopted value and the most recent measurement. In contrast to previous experiments, the present method was based on the (...)

Lire la suite

[in2p3-00467536] The β-γ decay of 21Na

12 avril 2010

A new and independent determination of the Gamow-Teller branching ratio in the β-decay of 21Na is reported. The value 5.13 ± 0.43% obtained is in agreement with the currently adopted value and the most recent measurement. In contrast to previous experiments, the present method was based on the (...)

Lire la suite

Migration of nuclear shell gaps studied in the d(24Ne,p gamma)25Ne reaction

12 avril 2010

The transfer of neutrons onto 24Ne has been measured using a reaccelerated radioactive beam of 24Ne to study the (d,p) reaction in inverse kinematics. The unusual raising of the first 3/2+ level in 25Ne and its significance in terms of the migration of the neutron magic number from N=20 to N=16 (...)

Lire la suite

[in2p3-00472413] Migration of nuclear shell gaps studied in the d(24Ne,p gamma)25Ne reaction

12 avril 2010

The transfer of neutrons onto 24Ne has been measured using a reaccelerated radioactive beam of 24Ne to study the (d,p) reaction in inverse kinematics. The unusual raising of the first 3/2+ level in 25Ne and its significance in terms of the migration of the neutron magic number from N=20 to N=16 (...)

Lire la suite

$^{6)$He + $^{9}$Be reactions at 16.8MeV

29 janvier 2010

Reactions of a 16.8 MeV 6He beam with a 9Be target have been investigated using highly segmented detector setup covering a large solid angle. Data on elastic and quasi-free scattering, as well as two-neutron transfer, are reported. The results for elastic scattering are fairly well reproduced (...)

Lire la suite

[in2p3-00451414] 6He + 9Be reactions at 16.8 MeV

29 janvier 2010

Reactions of a 16.8 MeV 6He beam with a 9Be target have been investigated using highly segmented detector setup covering a large solid angle. Data on elastic and quasi-free scattering, as well as two-neutron transfer, are reported. The results for elastic scattering are fairly well reproduced (...)

Lire la suite

Structure around the island of inversion with single-neutron knockout reactions at GANIL

20 janvier 2010

The nuclear structure of the 31Mg nucleus has been studied with the singleneutron knockout reaction. We report on the preliminary results of an experiment performed with the EXOGAM array coupled, for the first time, to the SPEG spectrometer at GANIL.We present a provisional result for the (...)

Lire la suite

Structure around the island of inversion with single-neutron knockout reactions at GANIL

20 janvier 2010

The nuclear structure of the 31Mg nucleus has been studied with the singleneutron knockout reaction. We report on the preliminary results of an experiment performed with the EXOGAM array coupled, for the first time, to the SPEG spectrometer at GANIL.We present a provisional result for the (...)

Lire la suite

Study of the $^{20}$O(d,t) reaction with the TIARA-MUST2-VAMOS-EXOGAM setup

6 janvier 2010

The reaction 20O(d,t) has been studied in inverse kinematics using a secondary ra- dioactive beam produced with the SPIRAL facility at GANIL. Fragments, light charged particles and gamma rays were measured with the TIARA, MUST2, VAMOS and EX- OGAM detectors and preliminary results are reported. (...)

Lire la suite

Study of the $^{20}$O(d,t) reaction with the TIARA-MUST2-VAMOS-EXOGAM setup

6 janvier 2010

The reaction 20O(d,t) has been studied in inverse kinematics using a secondary ra- dioactive beam produced with the SPIRAL facility at GANIL. Fragments, light charged particles and gamma rays were measured with the TIARA, MUST2, VAMOS and EX- OGAM detectors and preliminary results are reported. (...)

Lire la suite

Halo Structure of the Island of Inversion Nucleus 31Ne

5 janvier 2010

The cross sections for single-neutron removal from the very neutron-rich nucleus 31Ne on Pb and C targets have been measured at 230 MeV=nucleon using the RIBF facility at RIKEN. The deduced large Coulomb breakup cross section of 540(70) mb is indicative of a soft E1 excitation. Comparison with (...)

Lire la suite

[in2p3-00443978] Halo Structure of the Island of Inversion Nucleus 31Ne

5 janvier 2010

The cross sections for single-neutron removal from the very neutron-rich nucleus 31Ne on Pb and C targets have been measured at 230 MeV=nucleon using the RIBF facility at RIKEN. The deduced large Coulomb breakup cross section of 540(70) mb is indicative of a soft E1 excitation. Comparison with (...)

Lire la suite

Neutron Transfer Studied with a Radioactive beam of 24Ne, using TIARA at SPIRAL

4 janvier 2010

A general experimental technique for high resolution studies of nucleon transfer reactions using radioactive beams is briefly described, together with the first new physics results that have been obtained with the new TIARA array. These first results from TIARA are for the reaction (...)

Lire la suite

Neutron Transfer Studied with a Radioactive beam of 24Ne, using TIARA at SPIRAL

4 janvier 2010

A general experimental technique for high resolution studies of nucleon transfer reactions using radioactive beams is briefly described, together with the first new physics results that have been obtained with the new TIARA array. These first results from TIARA are for the reaction (...)

Lire la suite

On the possible detection of 4n events in the breakup of 14Be

27 novembre 2009

In a recent paper --F.M. Marques et al, PRC 65 (2002) 044006-- a new approach to the production and detection of free neutron clusters was proposed and applied to data acquired for the breakup of 14Be. Six events that exhibited characteristics consistent with a bound tetraneutron were observed (...)

Lire la suite

On the possible detection of 4n events in the breakup of 14Be

27 novembre 2009

In a recent paper --F.M. Marques et al, PRC 65 (2002) 044006-- a new approach to the production and detection of free neutron clusters was proposed and applied to data acquired for the breakup of 14Be. Six events that exhibited characteristics consistent with a bound tetraneutron were observed (...)

Lire la suite

Exploring the Southern Boundaries of the “Island of Inversion” at the RIBF

7 septembre 2009

The nuclear structure of neutron rich Ne isotopes has been investigated at the recently commissioned Radioactive Ion Beam Factory (RIBF) at the RIKEN Nishina Center by means of inelastic scattering and knockout reactions. A cocktail beam of unstable nuclei around 32Ne was provided by the (...)

Lire la suite

Exploring the Southern Boundaries of the “Island of Inversion” at the RIBF

7 septembre 2009

The nuclear structure of neutron rich Ne isotopes has been investigated at the recently commissioned Radioactive Ion Beam Factory (RIBF) at the RIKEN Nishina Center by means of inelastic scattering and knockout reactions. A cocktail beam of unstable nuclei around 32Ne was provided by the (...)

Lire la suite

Beam Diagnostics for SPIRAL2 RNB

1er septembre 2009

The SPIRAL2 project is based on a multi-beam driver facility in order to allow both ISOL and low-energy inflight techniques to produce intense radioactive ion beams (RIB) in a new Facility. A superconducting linac capable of accelerating 5-mA deuterons up to 40 MeV is used to bombard both thick (...)

Lire la suite

Beam Diagnostics for SPIRAL2 RNB

1er septembre 2009

The SPIRAL2 project is based on a multi-beam driver facility in order to allow both ISOL and low-energy inflight techniques to produce intense radioactive ion beams (RIB) in a new Facility. A superconducting linac capable of accelerating 5-mA deuterons up to 40 MeV is used to bombard both thick (...)

Lire la suite

TIARA: a large solid angle silicon array for direct reaction studies with radioactive beams

31 août 2009

A compact, quasi-4pi position sensitive silicon array, TIARA, designed to study direct reactions induced by radioactive beams in inverse kinematics is described here. The Transfer and Inelastic All-angle Reaction Array (TIARA) consists of 8 resistive-strip silicon detectors forming an octagonal (...)

Lire la suite

[in2p3-00411985] TIARA: a large solid angle silicon array for direct reaction studies with radioactive beams

31 août 2009

A compact, quasi-4pi position sensitive silicon array, TIARA, designed to study direct reactions induced by radioactive beams in inverse kinematics is described here. The Transfer and Inelastic All-angle Reaction Array (TIARA) consists of 8 resistive-strip silicon detectors forming an octagonal (...)

Lire la suite

Spectroscopy of 32Ne and the “Island of Inversion”

23 juillet 2009

We report on the first spectroscopic study of the N=22 nucleus 32Ne at the newly completed RIKEN Radioactive Ion Beam Factory. A single gamma-ray line with an energy of 722(9) keV was observed in both inelastic scattering of a 226 MeV/u 32Ne beam on a carbon target and proton removal from 33Na (...)

Lire la suite

[in2p3-00406584] Spectroscopy of 32Ne and the “Island of Inversion”

23 juillet 2009

We report on the first spectroscopic study of the N=22 nucleus 32Ne at the newly completed RIKEN Radioactive Ion Beam Factory. A single gamma-ray line with an energy of 722(9) keV was observed in both inelastic scattering of a 226 MeV/u 32Ne beam on a carbon target and proton removal from 33Na (...)

Lire la suite

Does transfer confirm knockout results for spectroscopic factor suppression with radioactive beams?

15 mai 2009

Proton removal measurements of the (e, e′p), (d,3He), and fast-beam knockout types show a consistent reduction of the spectroscopic factor when compared to shell model calculations [1-3]. The loss of single-particle strength is explained as the result of the short-range correlations between (...)

Lire la suite

Does transfer confirm knockout results for spectroscopic factor suppression with radioactive beams?

15 mai 2009

Proton removal measurements of the (e, e′p), (d,3He), and fast-beam knockout types show a consistent reduction of the spectroscopic factor when compared to shell model calculations [1-3]. The loss of single-particle strength is explained as the result of the short-range correlations between (...)

Lire la suite

New low-energy measurement of the 18F(p,α)15O reaction

23 avril 2009

The 18F, produced during nova explosions, is the main responsible for the 511 keV γ-ray emitted during the outburst that could be detected with satellite missions or future γ-ray telescopes. In spite of many experimental efforts, the amount of 18F synthesized still suffers from large uncertainties (...)

Lire la suite

New low-energy measurement of the 18F(p,α)15O reaction

23 avril 2009

The 18F, produced during nova explosions, is the main responsible for the 511 keV γ-ray emitted during the outburst that could be detected with satellite missions or future γ-ray telescopes. In spite of many experimental efforts, the amount of 18F synthesized still suffers from large uncertainties (...)

Lire la suite

Recent results from GANIL

30 mars 2009

The shell structure of the nucleus implies the existence of magic numbers. Since several years many indications have been accumulated, theoretically as well as through experiments at various laboratories around the world, that if one moves away from stability, the location of the magic numbers (...)

Lire la suite

Recent results from GANIL

30 mars 2009

The shell structure of the nucleus implies the existence of magic numbers. Since several years many indications have been accumulated, theoretically as well as through experiments at various laboratories around the world, that if one moves away from stability, the location of the magic numbers (...)

Lire la suite

Measurement of the Gamow-Teller Branching Ratio in the $\beta$-Decay of ${21}$Na

17 mars 2009

The beta-decay branching ratio of the GT transition in 21Na to the first excited state in 21Ne has been measured. The value obtained of 4.93(20)% is in agreement with the most recent measurement and with the value adopted so far. This confirms that the branching ratio is not the source of (...)

Lire la suite

Measurement of the Gamow-Teller Branching Ratio in the $\beta$-Decay of ${21}$Na

17 mars 2009

The beta-decay branching ratio of the GT transition in 21Na to the first excited state in 21Ne has been measured. The value obtained of 4.93(20)% is in agreement with the most recent measurement and with the value adopted so far. This confirms that the branching ratio is not the source of (...)

Lire la suite

Low-energy $^{18}$F( p, alpha)$^{15}$O cross section measurements relevant to nova $GAMMA$-ray emission

20 janvier 2009

During nova outbursts the decay of 18F is the main source of γ -ray emission at and below 511 keV. In spite of much experimental effort, the quantity of 18F synthesized still suffers from large uncertainties which arise mainly from the 18F(p, α)15O reaction cross section at low energies.We report (...)

Lire la suite

[in2p3-00354511] Low-energy $^{18}$F( p, alpha)$^{15}$O cross section measurements relevant to nova $GAMMA$-ray emission

20 janvier 2009

During nova outbursts the decay of 18F is the main source of γ -ray emission at and below 511 keV. In spite of much experimental effort, the quantity of 18F synthesized still suffers from large uncertainties which arise mainly from the 18F(p, α)15O reaction cross section at low energies.We report (...)

Lire la suite

Structure of the brunnian nucleus $^{10}$C

13 novembre 2008

The 2 ALPHA+ 2p breakup and structure of the only known Brunnian nucleus, 10C, has been studied at 33.3 MeV/nucleon. Detection of the 2ALPHA + 2p breakup fragments using a highly segmented Si-Si-Si-CsI detector array has allowed the 10C -> 9B -> p, 9B -> 8Be + p, 8Be -> (...)

Lire la suite

Direct mass measurements of $^{68}$Se and $^{80}$Y

22 juillet 2008

The masses of neutron-deficient nuclides near the N=Z line with A=64-80 have been determined using a direct time-of-flight technique which employed a cyclotron as a high-resolution spectrometer. The measured atomic masses for $^68$Se and $^80$Y were 67.9421(3) u and 79.9344(2) u, respectively. (...)

Lire la suite

Neutron-Neutron Correlations in the Dissociation of Halo Nuclei

7 mars 2008

Studies attempting to probe the spatial configuration of the valence neutrons in two-neutron halo nuclei using the technique of intensity interferometry are described. Following a brief review of the method and its application to earlier measurements of the breakup of $^6$He, $^11$Li and (...)

Lire la suite

Single-Proton Removal Reaction Study of $^{16}$B

29 février 2008

The low-lying level structure of the unbound system $^16$B has been investigated via single-proton removal from a 35 MeV/nucleon $^17$C beam. The coincident detection of the beam velocity $^15$B fragment and neutron allowed the relative energy of the in-flight decay of $^16$B to be (...)

Lire la suite

Evidence for core excitation in single-particle states of $^{19}$Na

5 février 2008

We present an experimental study of $^19$Na states in the excitation energy range between 2 and 3 MeV. The presence of $^19$Na single-particle levels at these energies was first predicted by a microscopic cluster model and then experimentally confirmed by measuring the elastic and inelastic (...)

Lire la suite

Breakup reaction study of the Brunnian nucleus $^{10}$C

5 février 2008

The structure and 2α + 2p breakup of $^10$C, the only known Brunnian nucleus, has been studied at 33.3 MeV/nucleon. The breakup kinematics were used to reconstruct the $^10$C→$^9$B +p, $^9$B→$^8$Be +p, $^8$Be→ α + α and $^10$C → $^6$Be +α, $^6$Be → $^5$Li +p, $^5$Li → α + p decay paths. Proton emission (...)

Lire la suite

Virtual coupling potential for elastic scattering of $^{10,11}$Be on proton and carbon targets

13 décembre 2007

The 10;11Be(p,p) and (12C, 12C) reactions were analyzed to determine the in uence of the weak binding energies of exotic nuclei on their interaction potential. The elastic cross sections were measured at GANIL in inverse kinematics using radioactive 10;11Be beams produced at energies of 39:1 A (...)

Lire la suite

Mass measurements of neutron-rich nuclei near the N=20 and 28 shell closures

30 mai 2007

Mass measurements of very neutron-rich nuclei near the N=20 and 28 shell closures are presented. Seven masses have been determined for the first time and the precision of 36 masses has been significantly improved. These results are used to investigate the evolution of the odd–even staggering of (...)

Lire la suite

B(E1) Strengths from Coulomb Excitation of $^{11}$Be

25 mai 2007

The $B$(E1;$1/2^+\to1/2^-$) strength for $^11$Be has been extracted from intermediate energy Coulomb excitation measurements, over a range of beam energies using a new reaction model, the extended continuum discretized coupled channels (XCDCC) method. In addition, a measurement of the (...)

Lire la suite

Collapse of the N=28 shell closure in $^{42}$Si

9 mai 2007

The energies of the excited states in very neutron-rich $^42$Si and $^41,43$P have been measured using in-beam$gamma$-ray spectroscopy from the fragmentation of secondary beams of $^42,44$S at 39 A.MeV. The low $2^+ $ energy of $^42$Si, 770(19) keV, together with the level schemes of $^41,43$P (...)

Lire la suite

Extended sudden approximation model for high-energy nucleon removal reactions

5 février 2007

A model based on the sudden approximation has been developed to describe high energy single nucleon removal reactions. Within this approach, which takes as its starting point the formalism of Hansen \citeAnne2, the nucleon-removal cross section and the full 3-dimensional momentum distributions (...)

Lire la suite

Coupling effects in the elastic scattering of $^{6}$He on $^{12}$C

21 décembre 2006

To study the effect of the weak binding energy on the interaction potential between a light exotic nucleus and a target, elastic scattering of 6He at 38.3 MeV/nucleon on a 12C target was measured at Grand Accélérateur National d'Ions Lourds (GANIL). The 6He beam was produced by fragmentation. The (...)

Lire la suite

Radiative proton capture on $^6$He

8 novembre 2006

Radiative capture of protons is investigated as a probe of clustering in nuclei far from stability. The first such measurement on a halo nucleus is reported here for the reaction $^6$He(p,$\gamma$) at 40 MeV. Capture into $^7$Li is observed as the strongest channel. In addition, events have (...)

Lire la suite

Clustering and Correlations at the Neutron Dripline

10 juillet 2006

Some recent experimental studies of clustering and correlations within very neutron-rich light nuclei are reviewed. In particular, the development of the novel probes of neutron-neutron interferometry and Dalitz-plot analyses is presented through the example of the dissociation of the (...)

Lire la suite

Probing Halo and Molecular States in Light, Neutron-Rich Nuclei

10 juillet 2006

Selected topics on halo and molecular states in light, neutron-rich nuclei are discussed. In particular, work on $x\alpha$:X$n$ structures is briefly reviewed. The use of proton radiative capture as a probe of clustering is also presented through the example provided by the $^6$He(p,$\gamma$) (...)

Lire la suite

Clustering and Correlations in Neutron Haloes

10 juillet 2006

In the present paper clustering and correlations within halo systems is explored. In particular, the application of neutron-neutron interferometry and Dalitz-plot type analyses is presented through the example provided by the dissociation of 14Be. A novel approach for producing and detecting (...)

Lire la suite

Nuclear Halo and Molecular States

10 juillet 2006

Significant advances have been made in recent years in the exploration of clustering in light nuclei. This progress has arisen not only from the investigation of new systems, but also through the development and application of novel probes. This paper will briefly review selected topics (...)

Lire la suite

Three-body correlations in Borromean halo nuclei

10 juillet 2006

Three-body correlations in the dissociation of Borromean halo nuclei are explored for the first time using a technique based on intensity interferometry and Dalitz plots. As an example, the breakup of $^14$Be into $^12$Be+n+n by Pb and C targets is analysed. The combined treatment of n-n and (...)

Lire la suite

Structure of $^{12}$Be : intruder d-wave strength at N=8

17 février 2006

The breaking of the N=8 shell-model magic number in the $^12$Be ground state has been determined to include significant occupancy of the intruder d-wave orbital. This is in marked contrast with all other N=8 isotones, both more and less exotic than $^12$Be. The occupancies of the 0hw vp$_1/2$ (...)

Lire la suite

The $^7Be(d,p)2\alpha$ cross section at Big Bang energies and the primordial $^7$Li abundance

26 septembre 2005

The WMAP satellite, devoted to the observations of the anisotropies of the Cosmic Microwave Background (CMB) radiation, has recently provided a determination of the baryonic density of the Universe with unprecedented precision. Using this, Big Bang Nucleosynthesis (BBN) calculations predict a (...)

Lire la suite

Study of 19Na at SPIRAL

5 septembre 2005

The excitation function for the elastic-scattering reaction p18Ne, p18Ne was measured with the first radioactive beam from the SPIRAL facility at the GANIL laboratory and with a solid cryogenic hydrogen target. Several broad resonances have been observed, corresponding to new excited states in (...)

Lire la suite

The halo of $^{14}$Be

19 avril 2005

The two-neutron halo nucleus 14Be has been investigated in a kinematically complete measurement of the fragments (12Be and neutrons) produced in dissociation at 35 MeV/nucleon on C and Pb targets. Two-neutron removal cross-sections, neutron angular distributions and invariant mass spectra (...)

Lire la suite

Single-neutron transfer from $^{11}$Be$_{gs}$ via the (p,d) reaction with a radioactive beam

5 mars 2001

The 11Be(p,d)10Be reaction has been performed in inverse kinematics with a radioactive 11Be beam of E/A = 35.3 MeV. Angular distributions for the 0+ ground state, the 2+, 3.37 MeV state and the multiplet of states around 6 MeV in 10Be were measured at angles up to 16 deg CM by detecting the (...)

Lire la suite

Crossing the dripline to $^{11}$N using elastic resonance scattering

4 octobre 2000

The level structure of the unbound nucleus 11N has been studied by 10C+p elastic resonance scattering in inverse geometry with the LISE3 spectrometer at GANIL, using a 10C beam with an energy of 9.0 MeV/u. An additional measurement was done at the A1200 spectrometer at MSU. The excitation (...)

Lire la suite