-
H. Ueno,
H. Miyatake,
Y. Yamamoto,
S. Tanimoto,
T. Shimoda,
N. Aoi,
K. Asahi,
E. Ideguchi,
M. Ishihara,
H. Izumi, [......], T. Kubo,
S. Mitsuoka,
Y. Mizoi,
M. Notani,
H. Ogawa,
A. Ozawa,
M. Sasaki,
T. Shirakura,
N. Takahashi,
K. Yoneda
[show abstract]
[hide abstract]
ABSTRACT: Excited states in 17C were investigated through the measurement of
beta?-delayed neutrons and gamma rays emitted in the ? decay of 17B. In the
measurement, three negative-parity states and two inconclusive states, were
identified in 17C above the neutron threshold energy, and seven gamma-lines
were identified in a beta?-delayed multiple neutron emission of the 17B ?
decay. From these transitions, the beta?-decay scheme of 17B was determined. In
the present work, the ?beta-NMR technique is combined with the ?-delayed
particle measurements using a fragmentation-induced spin-polarized 17B beam.
This new scheme allows us to determine the spin parity of beta?-decay feeding
excited states based on the difference in the discrete ?beta-decay asymmetry
parameters, provided the states are connected through the Gamow-Teller
transition. In this work, 1/2-, 3/2-, and (5/2-) are assigned to the observed
states at Ex = 2.71(2), 3.93(2), and 4.05(2) MeV in 17C, respectively.
01/2013;
-
Y. Ichikawa,
H. Ueno,
Y. Ishii,
T. Furukawa,
A. Yoshimi,
D. Kameda,
H. Watanabe,
N. Aoi,
K. Asahi,
D. L. Balabanski, [......],
N. Inabe,
T. Inoue,
M. Ishihara, T. Kubo,
T. Nanao,
T. Ohnishi,
K. Suzuki,
M. Tsuchiya,
H. Takeda,
M. M. Rajabali
[show abstract]
[hide abstract]
ABSTRACT: The degree of freedom of spin in quantum systems serves as an unparalleled
laboratory where intriguing quantum physical properties can be observed, and
the ability to control spin is a powerful tool in physics research. We propose
a novel method for controlling spin in a system of rare isotopes which takes
advantage of the mechanism of the projectile fragmentation reaction combined
with the momentum-dispersion matching technique. The present method was
verified in an experiment at the RIKEN RI Beam Factory, in which a degree of
alignment of 8% was achieved for the spin of a rare isotope Al-32. The figure
of merit for the present method was found to be greater than that of the
conventional method by a factor of more than 50.
11/2012;
-
D. Kameda, T. Kubo,
T. Ohnishi,
K. Kusaka,
A. Yoshida,
K. Yoshida,
M. Ohtake,
N. Fukuda,
H. Takeda,
K. Tanaka, [......],
A. Ozawa,
T. Ohtsubo,
M. A. Famiano,
H. Geissel,
A. S. Nettleton,
O. B. Tarasov,
D. Bazin,
B. M. Sherrill,
S. L. Manikonda,
J. A. Nolen
[show abstract]
[hide abstract]
ABSTRACT: A search for isomeric gamma-decays among fission fragments from 345
MeV/nucleon 238U has been performed at the RIKEN Nishina Center RI Beam
Factory. Fission fragments were selected and identified using the
superconducting in-flight separator BigRIPS and were implanted in an aluminum
stopper. Delayed gamma-rays were detected using three clover-type high-purity
germanium detectors located at the focal plane within a time window of 20
microseconds following the implantation. We identified a total of 54
microsecond isomers with half-lives of ~0.1 - 10 microseconds, including
discovery of 18 new isomers in very neutron-rich nuclei: 59Tim, 90Asm, 92Sem,
93Sem, 94Brm, 95Brm, 96Brm, 97Rbm, 108Nbm, 109Mom, 117Rum, 119Rum, 120Rhm,
122Rhm, 121Pdm, 124Pdm, 124Agm and 126Agm, and obtained a wealth of
spectroscopic information such as half-lives, gamma-ray energies, gamma-ray
relative intensities and gamma-gamma coincidences over a wide range of
neutron-rich exotic nuclei. Proposed level schemes are presented for 59Tim,
82Gam, 92Brm, 94Brm, 95Brm, 97Rbm, 98Rbm, 108Nbm, 108Zrm, 109Mom, 117Rum,
119Rum, 120Rhm, 122Rhm, 121Pdm, 124Agm and 125Agm, based on the obtained
spectroscopic information and the systematics in neighboring nuclei. Nature of
the nuclear isomerism is discussed in relation to evolution of nuclear
structure.
11/2012;
-
O. B. Tarasov,
D. J. Morrissey,
A. M. Amthor,
L. Bandura,
T. Baumann,
D. Bazin,
J. S. Berryman,
G. Chubarian,
N. Fukuda,
A. Gade, [......],
M. Hausmann,
N. Inabe, T. Kubo,
J. Pereira,
M. Portillo,
B. M. Sherrill,
A. Stolz,
C. Sumithrarachchi,
M. Thoennessen,
D. Weisshaar
[show abstract]
[hide abstract]
ABSTRACT: Production cross sections for neutron-rich nuclei from the fragmentation of a
82Se beam at 139 MeV/u were measured. The longitudinal momentum distributions
of 122 neutron-rich isotopes of elements $11 \le Z \le 32$ were determined by
varying the target thickness. Production cross sections with beryllium and
tungsten targets were determined for a large number of nuclei including several
isotopes first observed in this work. These are the most neutron-rich nuclides
of the elements $22 \le Z \le 25$ (64Ti, 67V, 69Cr, 72Mn). One event was
registered consistent with 70Cr, and another one with 75Fe. A one-body Qg
systematics is used to describe the production cross sections based on thermal
evaporation from excited prefragments. The current results confirm those of our
previous experiment with a 76Ge beam: enhanced production cross sections for
neutron-rich fragments near Z=20.
09/2012;
-
M. Niikura,
E. Ideguchi,
N. Aoi,
H. Baba,
T. Fukuchi,
Y. Ichikawa,
H. Iwasaki, T. Kubo,
M. Kurokawa,
M. Liu,
S. Michimasa,
T. Ohnishi,
T. K. Onishi,
S. Ota,
S. Shimoura, H. Suzuki,
D. Suzuki,
Y. Wakabayashi,
K. Yoshida,
Y. Zheng
[show abstract]
[hide abstract]
ABSTRACT: In-beam g \gamma -ray spectroscopy of high-spin states in 49-51Ti was performed via the fusion-evaporation reaction using a radioactive beam. By excitation function and g \gamma -g \gamma coincidence analysis, yrast high-spin levels up to I = (21/2-),(11+),(17/2-) in 49-51Ti were determined. The levels were compared with full-pf -shell model calculation. The level structure indicates the persistency of the N = 28 shell gap at yrast states in 49-51Ti .
European Physical Journal A 05/2012; 42(3):471-475. · 2.19 Impact Factor
-
M. Mihara,
T. Izumikawa,
H. Ueno,
K. Matsuta,
D. Nishimura,
T. Nagatomo,
T. Moriguchi,
Y. Ito,
D. Nagae,
M. Fukuda, [......],
D. Horikawa,
T. Minamisono,
T. Yamaguchi,
T. Kuboki,
T. Suzuki,
K. Satoh,
Y. Kobayashi,
K. Asahi,
K. Matsukawa,
K. Shirai
[show abstract]
[hide abstract]
ABSTRACT: The β-NMR study of short-lived nucleus 58Cu (I
π
= 1 + , T
1/2 = 3.2s) in Si has been performed. Spin polarization of 58Cu induced by the charge exchange reaction of 58Ni was observed in Si at 15 K. The 58Cu magnetic moment
|\upmu[58Cu]| = (0.46 ±0.03)\upmuN|\upmu[^{58}\mbox{Cu}]| = (0.46 \pm 0.03)\upmu_{\rm N} deduced from the β-NMR spectrum is consistent with the previous results on the laser spectroscopy. The present result shows
that the 58Cu nucleus is promising as a new nuclear probe for the microscopic study of Cu impurities in Si.
Keywordsβ-NMR–
58Cu–Magnetic moment–Silicon–Cu impurity
Hyperfine Interactions 05/2012; 197(1):143-147. · 0.21 Impact Factor
-
Y. Ichikawa, T. Kubo,
N. Aoi,
V. Banerjee,
A. Chakrabarti,
N. Fukuda,
H. Iwasaki,
S. Kubono,
T. Motobayashi,
T. Nakabayashi, [......],
T. Okumura,
H. J. Ong,
T. K. Onishi,
D. Suzuki,
H. Suzuki,
M. K. Suzuki,
T. Teranishi,
K. N. Yamada,
H. Yamaguchi,
H. Sakurai
[show abstract]
[hide abstract]
ABSTRACT: b \beta -decay spectroscopy on a T
z = - 2 proton-rich nucleus 24Si was performed. The decay scheme of 24Si was reconstructed by the b \beta -delayed g \gamma -ray and proton measurements. Two b \beta branches to the bound 11
+ and 12
+ states in 24Al were observed for the first time. The observation of the allowed transition firmly established the spin-parity assignment
for the 12
+ states. The branching ratios to the 11
+ and 12
+ states were determined to be 31(4)% and 23.9(15)%, respectively. The branching ratios to three unbound states in 24Al including a new level at 6.735MeV were also determined for the first time. The level structure of 24Al was compared with its mirror nucleus 24Na . The Thomas-Ehrman shift on the 12
+ state indicates s -wave dominance in the state as well as a characteristic behavior of the weakly bound s -wave proton in 24Al .
European Physical Journal A 04/2012; 42(3):375-378. · 2.19 Impact Factor
-
R Chevrier,
J M Daugas,
L Gaudefroy,
Y Ichikawa,
H Ueno,
M Hass,
H Haas,
S Cottenier,
N Aoi,
K Asahi, [......],
T Nanao,
G Neyens,
T Ohnishi,
M M Rajabali,
K Suzuki,
H Takeda,
M Tsuchiya,
N Vermeulen,
H Watanabe,
A Yoshimi
[show abstract]
[hide abstract]
ABSTRACT: We report on the spectroscopic quadrupole moment measurement of the 7/2(1)(-) isomeric state in (16)(43)S(27) [E*=320.5(5) keV, T(1/2)=415(3) ns], using the time dependent perturbed angular distribution technique at the RIKEN RIBF facility. Our value, |Q(s)|=23(3) efm(2), is larger than that expected for a single-particle state. Shell model calculations using the modern SDPF-U interaction for this mass region reproduce remarkably well the measured |Q(s)|, and show that non-negligible correlations drive the isomeric state away from a purely spherical shape.
Physical Review Letters 04/2012; 108(16):162501. · 7.37 Impact Factor
-
N Kobayashi,
T Nakamura,
J A Tostevin,
Y Kondo,
N. Aoi,
H Baba,
S. Deguchi,
J Gibelin,
M Ishihara,
Y Kawada, [......],
Y Satou,
E. C. Simpson,
T. Sumikama,
H Takeda,
M Takechi,
S Takeuchi,
K. N. Tanaka,
N Tanaka,
Y. Togano,
K Yoneda
[show abstract]
[hide abstract]
ABSTRACT: 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
observed for one-neutron removal from $^{19}$C and $^{20}$C and two-neutron
removal from $^{22}$C. Two-neutron removal from $^{20}$C resulted in a
relatively broad momentum distribution. The results are compared with
eikonal-model calculations combined with shell-model structure information. The
neutron-removal cross sections and associated momentum distributions are
calculated for transitions to both the particle-bound and particle-unbound
final states. The calculations take into account the population of the mass
$A-1$ reaction residues, $^{A-1}$C, and, following one-neutron emission after
one-neutron removal, the mass $A-2$ two-neutron removal residues, $^{A-2}$C.
The smaller contributions of direct two-neutron removal, that populate the
$^{A-2}$C residues in a single step, are also computed. The data and
calculations are shown to be in good overall agreement and consistent with the
predicted shell-model ground state configurations and the one-neutron overlaps
with low-lying states in $^{18-21}$C. These suggest significant
$\nu{s}_{1/2}^2$ valence neutron configurations in both $^{20}$C and $^{22}$C.
The results for $^{22}$C strongly support the picture of $^{22}$C as a
two-neutron halo nucleus with a dominant $\nu{s}_{1/2}^2$ ground state
configuration.
11/2011;
-
T Uesaka,
S Michimasa,
S Ota,
A Saito,
K Nakanishi,
Y Sasamoto,
K Miki,
S Noji,
H Tokieda,
H Miya, [......],
D Kameda, T Kubo,
M Sasano,
H Baba,
K Itahashi,
G P A Berg,
D Bazin,
P Roussel-Chomaz,
Y Shimbara,
M Nagashima
[show abstract]
[hide abstract]
ABSTRACT: The high-resolution SHARAQ spectrometer and the dedicated beam-line have been constructed at the RI beam factory. Cathode-readout drift chambers placed at the focal plane of SHARAQ and multi-wire drift chambers in the beam-line worked satisfactorily for heavy ion beams with Z = 1–7 at 200–250 MeV/nucleon. By introducing a dispersion matched operation of the beam-line, we have achieved a momentum resolution of Δp/p = 1/8100 for a primary beam of 14N beam with a momentum spread of ±0.1%.
Journal of Physics Conference Series 09/2011; 312(5):052028.
-
Y Shimizu,
T Kobayashi, T Kubo,
N Chiga,
T Isobe,
T Kawabata,
Y Kondo,
K Kusaka,
Y Matsuda,
T Motobayashi, [......],
J Ohnishi,
T Ohnishi,
H Okuno,
H Otsu,
H Sakurai,
H Sato,
Y Satou,
K Sekiguchi,
Y Togano,
K Yoneda
[show abstract]
[hide abstract]
ABSTRACT: SAMURAI project aims to open a new research field in nuclear physics by the use of a large acceptance spectrometer for kinematically complete measurements of multiple particles emitted in RI-beam induced reactions. The SAMURAI spectrometer consists of a large gap superconducting dipole magnet, heavy ion detectors, neutron detectors, and proton detectors. What is special about the SAMURAI system is that projectile-rapidity protons or neutrons are detected with large angular and momentum acceptance in coincidence with heavy projectile fragments. With an effective combination of these equipments, the SAMURAI system allows us to perform various experiments: electromagnetic dissociation, various direct reactions, polarized deuteron induced reactions, and EOS studies. SAMURAI project is currently underway at RIBF. The construction of the superconducting dipole magnet will start in autumn 2010 and finish in spring 2011. The detectors are also being constructed in parallel. The first commissioning run will be performed in early 2012.
Journal of Physics Conference Series 09/2011; 312(5):052022.
-
K Miki,
H Sakai,
T Uesaka,
H Baba,
G P A Berg,
N Fukuda,
D Kameda,
T Kawabata,
S Kawase, T Kubo, [......],
S Ota,
A Saito,
Y Sasamoto,
M Sasano,
S Shimoura,
H Takeda,
H Tokieda,
K Yako,
Y Yanagisawa,
R G T Zegers
[show abstract]
[hide abstract]
ABSTRACT: The isovector spin monopole resonances (IVSMR) of the β+ type were observed via the 208Pb and 90Zr(t, 3He) reactions at 300 MeV/u. The experiment was performed at the RI Beam Factory (RIBF) at RIKEN by using the newly-constructed magnetic spectrometer SHARAQ. The double differential cross sections for the 208Pb and 90Zr(t, 3He) reactions were obtained at the excitation energy of 0 ≤ Ex ≤ 70 MeV and the scattering angles of 0° ≤ 9 ≤ 3°. The monopole component was obtained as a difference between the zero-degree and backward-angle spectra. The signatures for the IVSMR were discovered at excitation energies of 12 MeV and 20 MeV in 208Pb and 90Zr, respectively, and they show good correspondences to the theoretical predictions.
Journal of Physics Conference Series 09/2011; 312(9):092040.
-
Y Togano,
T Gomi,
T Motobayashi,
Y Ando,
N Aoi,
H Baba,
K Demichi,
Z Elekes,
N Fukuda,
Zs Fülöp, [......],
M Serata,
S Shimoura,
T Sugimoto,
E Takeshita,
S Takeuchi,
K Ue,
K Yamada,
Y Yanagisawa,
K Yoneda,
A Yoshida
[show abstract]
[hide abstract]
ABSTRACT: The stellar reaction 26 Si(p,γ) 27 P was studied in the Coulomb dissociation of 27 P. Two known resonance levels in 27 P were excited and a candidate for the third excited state was found in the 26 Si p relative energy spectrum. The E2 resonance strengths ωγ were obtained to be (6.5 ± 1.3) × 10 −11 , (6.0 ± 1.1) × 10 −10 , and (1.10 ± 0.27) × 10 −10 MeV. The total (E2 + M1) ωγ value for the first excited state was evaluated to be 1.9 +1.9 −1.1 × 10 −9 MeV with the help of the shell model. The error was estimated from the deviation of theoretical predictions with the same shell model from experimental strengths obtained in the present study for 27 P and earlier ones for the mirror nucleus 27 Mg. The astrophysical reaction rate for the 26 Si(p,γ) 27 P reaction was also calculated and compared with previous estimations.
Physical Review C 01/2011; 035808(84). · 3.31 Impact Factor
-
N. Aoi,
S Kanno,
S Takeuchi,
H Suzuki,
D. Bazin,
M D Bowen,
C M Campbell,
J M Cook,
D C Dinca,
A Gade, [......], T Kubo,
K Kurita,
T. Motobayashi,
W. F. Mueller,
T Nakamura,
H Sakurai,
M. Takashina,
J R Terry,
K Yoneda,
H. Zwahlen
[show abstract]
[hide abstract]
ABSTRACT: The neutron-rich nucleus 74Ni was studied with inverse-kinematics inelastic proton scattering using a 74Ni radioactive beam incident on a liquid hydrogen targetat a center-of-mass energy of 80 MeV. From the measured de-excitation gamma-rays, the population of the first 2+ state was quantified. The angle-integrated excitation cross section was determined to be 14(4) mb. A deformation length of delta = 1.04(16) fm was extracted in comparison with distorted wave theory, which suggests that the enhancement of collectivity established for 70Ni continues up to 74Ni. A comparison with results of shell model and quasi-particle random phase approximation calculations indicates that the magic character of Z = 28 or N = 50 is weakened in 74Ni.
08/2010;
-
Y. Ichikawa,
T. K. Onishi,
D. Suzuki,
H. Iwasaki, T. Kubo,
V. Naik,
A. Chakrabarti,
N. Aoi,
B. A. Brown,
N. Fukuda, [......],
T. Nakamura,
T. Nakao,
T. Okumura,
H. J. Ong,
H. Suzuki,
M. K. Suzuki,
T. Teranishi,
K. N. Yamada,
H. Yamaguchi,
H. Sakurai
[show abstract]
[hide abstract]
ABSTRACT: The Gamow‐Teller transition strength B(GT) of 24Si was measured to investigate characteristic structure of proton‐rich nuclei induced by a weakly‐bound proton. By combining the results of the delayed γ‐ray and proton measurements, the entire decay scheme of 24Si was reconstructed, then the B(GT) of 24Si was deduced. Focusing to the low‐lying states, the B(GT) of 24Si to the 11+ and 12+ states in 24Al were smaller than that of the mirror nucleus 24Ne by 22% and 10%, respectively. The mirror asymmetry of B(GT) indicates the configuration change in the wave function. Through the comparison with theoretical shell‐model calculations, it is implied that the configuration change is attributed to the lowering of the 1s1/2 orbital. The applicability of the theoretical calculations was checked using overall B(GT) distribution.
AIP Conference Proceedings. 05/2010; 1235(1):265-269.
-
T. Uesaka,
S. Michimasa,
S. Ota,
A. Saito,
K. Nakanishi,
Y. Sasamoto,
H. Miya,
H. Tokieda,
S. Kawase,
Y. Shimizu, [......], T. Kubo,
M. Sasano,
H. Baba,
K. Itahashi,
T. Ichihara,
G. P. A. Berg,
P. Roussel‐Chomaz,
D. Bazin,
Y. Shimbara,
M. Nagashima
[show abstract]
[hide abstract]
ABSTRACT: The high‐resolution SHARAQ spectrometer and the dedicated high‐resolution beamline have been constructed at RI beam factory and commissioned in 2009. Lateral and angular dispersion matching conditions were achieved simultaneously for a primay beam with a momentum spread of 0.1% and an emittance of 3π mm⋅mrad (σ). An overview of the spectrometer and the beam‐line, preliminary results from the commissioning runs, and future experimental plan with the system are described.
AIP Conference Proceedings. 04/2010; 1224(1):573-581.
-
K Tanaka,
T Yamaguchi,
T Suzuki,
T Ohtsubo,
M Fukuda,
D Nishimura,
M Takechi,
K Ogata,
A Ozawa,
T Izumikawa, [......],
H Sakurai,
R Shinoda,
M Shinohara,
H Suzuki,
E Takeshita,
S Takeuchi,
Y Togano,
K Yamada,
T Yasuno,
M Yoshitake
[show abstract]
[hide abstract]
ABSTRACT: Reaction cross sections (sigma(R)) for 19C, 20C and the drip-line nucleus 22C on a liquid hydrogen target have been measured at around 40A MeV by a transmission method. A large enhancement of sigma(R) for 22C compared to those for neighboring C isotopes was observed. Using a finite-range Glauber calculation under an optical-limit approximation the rms matter radius of 22C was deduced to be 5.4+/-0.9 fm. It does not follow the systematic behavior of radii in carbon isotopes with N < or = 14, suggesting a neutron halo. It was found by an analysis based on a few-body Glauber calculation that the two-valence neutrons in 22C preferentially occupy the 1s(1/2) orbital.
Physical Review Letters 02/2010; 104(6):062701. · 7.37 Impact Factor
-
T Nakamura,
N Kobayashi,
Y Kondo,
Y Satou,
N Aoi,
H Baba,
S Deguchi,
N Fukuda,
J Gibelin,
N Inabe, [......],
M Takechi,
S Takeuchi,
K Tanaka,
K N Tanaka,
N Tanaka,
Y Togano,
Y Utsuno,
K Yoneda,
A Yoshida,
K Yoshida
[show abstract]
[hide abstract]
ABSTRACT: 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 direct-breakup model calculations suggests that the valence neutron of 31Ne occupies a low-l orbital (most probably 2p(3/2)) with a small separation energy (S(n) approximately < 0.8 MeV), instead of being predominantly in the 1f(7/2) orbital as expected from the conventional shell ordering. These findings suggest that 31Ne is the heaviest halo system known.
Physical Review Letters 12/2009; 103(26):262501. · 7.37 Impact Factor
-
Y. Ichikawa,
T. K. Onishi,
D. Suzuki,
H. Iwasaki, T. Kubo,
V. Naik,
A. Chakrabarti,
N. Aoi,
B. A. Brown,
N. Fukuda, [......],
T. Nakamura,
T. Nakao,
T. Okumura,
H. J. Ong,
H. Suzuki,
M. K. Suzuki,
T. Teranishi,
K. N. Yamada,
H. Yamaguchi,
H. Sakurai
[show abstract]
[hide abstract]
ABSTRACT: β-decay spectroscopy of the proton-rich nucleus 24Si was performed. The decay scheme was reconstructed from results of delayed γ-ray and proton measurements. We observed two β branches to bound states in 24Al for the first time. The branching ratios were determined to be 31(4)% and 23.9(15)% for the 11+ state at 0.426 MeV and the state at 1.090 MeV, respectively. The observation of an allowed transition to the 1.090-MeV state enabled us to firmly determine its spin-parity as 1+. In the proton measurements performed with the ΔE-E method, we observed a new unbound level at 6.735 MeV. The branching ratios to three unbound states, including the new level, were also determined for the first time. Based on the decay scheme, the B(GT) values of 24Si were deduced. The B(GT) values were smaller than those of the mirror nucleus 24Ne by 22% and 10% for the 11+ and 12+ states, respectively. The mirror asymmetries of B(GT), observed in both the 11+ and the 12+ states, indicate changes in configuration in the wave function associated with the Thomas-Ehrman shift. To clarify the mechanism of this asymmetry, a comparison with shell-model calculations is also discussed. The calculations attribute the changes in configuration to the lowering of the 1s1/2 orbital.
Physical Review C 10/2009; 80(4):044302. · 3.31 Impact Factor
-
O. B. Tarasov,
M. Portillo,
A. M. Amthor,
T. Baumann,
D. Bazin,
A Gade,
T. N. Ginter,
M. Hausmann,
N. Inabe, T Kubo,
D. J. Morrissey,
A. Nettleton,
J. Pereira,
B. M. Sherrill,
A. Stolz,
M. Thoennessen
[show abstract]
[hide abstract]
ABSTRACT: Production cross sections for neutron-rich nuclei from the fragmentation of a 76Ge beam at 132 MeV/u were measured. The longitudinal momentum distributions of 34 neutron-rich isotopes of elements 13 <= Z <= 27 were scanned using a novel experimental approach of varying the target thickness. Production cross sections with beryllium and tungsten targets were determined for a large number of nuclei including 15 isotopes first observed in this work. These are the most neutron-rich nuclides of the elements 17 <= Z <= 25 (50Cl, 53Ar, 55,56K, 57,58Ca, 59,60,61Sc, 62,63Ti, 65,66V, 68Cr,70Mn). A one-body Qg systematics is used to describe the production cross sections based on thermal evaporation from excited prefragments. Some of the fragments near 58Ca show anomalously large production cross sections. Comment: accepted for publication in Phys.Rev.C
08/2009;
