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Recent interest in g-factor measurements in neutron-deficient 76Kr has stimulated the development of this radioactive beam at the 88-Inch Cyclotron at the Lawrence Berkeley National Laboratory. The 14.8 hour half life allows the... more
Recent interest in g-factor measurements in neutron-deficient 76Kr has stimulated the development of this radioactive beam at the 88-Inch Cyclotron at the Lawrence Berkeley National Laboratory. The 14.8 hour half life allows the production of this beam in a two step-process (Berkeley re-cyclotron method). First, ^76Kr is produced via the reaction ^74Se(,2n) ^76Kr using a 7 particle microampere, 57 MeV
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Research Interests: Physics, Atomic Physics, Medicine, Physical sciences, Scattering, and 4 moreProton, Photon, Compton Scattering, and Pion
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ABSTRACT Background: Single-particle and collective modes of nuclear excitation compete in the isotopes of the elements _{30}Zn, _{32}Ge, _{34}Se, _{36}Kr, and _{38}Sr.Purpose: To study the factors which determine the onset of... more
ABSTRACT Background: Single-particle and collective modes of nuclear excitation compete in the isotopes of the elements _{30}Zn, _{32}Ge, _{34}Se, _{36}Kr, and _{38}Sr.Purpose: To study the factors which determine the onset of collectivity in this region.Methods: Data obtained from National Nuclear Data Center compilations supplemented by recent measurements of excitation energies and B(E2) reduced transition probabilities between the low-lying states in these elements were examined. The data were analyzed as a function of the neutron number N as well as the parameter P=N_{p}N_{n}/(N_{p}+N_{n}) related to the number of valence protons and neutrons, N_{p} and N_{n}, in the 28≤Z,N≤50 shell.Results: The systematics of the data show variations ranging from mostly single-particle to collective excitations.Conclusions: Collectivity sets in when the number of both protons and neutrons lie near the middle of the shell 30≤Z,N≤50. Backbends appear in the data showing that particles and holes in the major shell behave differently. The 2_{2}^{+} states exhibit single particle behavior. The transition probabilities of the 2_{2}^{+} states in the Kr isotopes differ significantly from the systematics.
A first direct g-factor measurement of superdeformed (SD) bands in ^194Hg(Bull. Am. Phys. Soc. 41), 1238 (1996). has been carried out utilizing the Gammasphere array at LBNL and the transient-field technique.(N. Benczer-Koller et al.,... more
A first direct g-factor measurement of superdeformed (SD) bands in ^194Hg(Bull. Am. Phys. Soc. 41), 1238 (1996). has been carried out utilizing the Gammasphere array at LBNL and the transient-field technique.(N. Benczer-Koller et al., Ann. Rev. Nuc. Part. Sci. 30), 53 (1980). The SD bands were populated with the ^150Nd(^48Ca,4n) reaction at 203 MeV. Angular distributions of gamma rays de-exciting
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The Se and Kr isotopes differ by two protons but span the same range of neutron numbers, 40<N<50. Precision g factor measurements in _34^74-82Se indicated that N = 38 represents a better subshell closure than N = 28 or 50. How does... more
The Se and Kr isotopes differ by two protons but span the same range of neutron numbers, 40<N<50. Precision g factor measurements in _34^74-82Se indicated that N = 38 represents a better subshell closure than N = 28 or 50. How does the addition of two protons affect the structure? The g factors of the 2^+1 states in _36^78-86Kr were
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B(E2) values have been determined for excited states of ^144,146Nd using Coulomb excitation on a thick target. The experiment was conducted at the Lawrence Berkeley National Laboratory, using the 8pi detector array, consisting of 20... more
B(E2) values have been determined for excited states of ^144,146Nd using Coulomb excitation on a thick target. The experiment was conducted at the Lawrence Berkeley National Laboratory, using the 8pi detector array, consisting of 20 Compton-suppressed Ge detectors. 500 MeV ^144,146Nd beams were directed onto thick ^natNi and ^natPb targets. Gamma yields for several states, relative to the 2^+ arrow
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ABSTRACT Summary Precessions of the angular distribution of numerous transitions in three normal deformation bands in194,193Hg, as well as of high-excitationM1/E2 transitions, were determined in a transient field experiment conducted at... more
ABSTRACT Summary Precessions of the angular distribution of numerous transitions in three normal deformation bands in194,193Hg, as well as of high-excitationM1/E2 transitions, were determined in a transient field experiment conducted at the Berkeley 88″ Cyclotron with the Gammasphere array. The reaction150Nd(48Ca,4n-5n)194,193Hg at a beam energy of 203 MeV was used to populate high-spin levels and to provide recoiling reaction-product nuclei with sufficient velocity to traverse a gadolinium ferromagnetic layer. The average precession of the observed γ-ray transitions reflects the precession of the magnetic moment of higher, unobservable quasicontinuum states which feed these states. The resulting averageg-factors obtained for the three main decay paths in each of the193,194Hg isotopes are: 〈g(193Hg)〉 = 0.19(1) and 〈g(194Hg)〉 = 0.26(1). For theM1/E2 transitions the results are: 〈g(193Hg)〉 = 0.24(5) and 〈g(194Hg)〉 = 0.26(4), respectively. The reduction of the averageg-factors in even isotopes compared to the naiveZ/A value, and the further reduction in odd isotopes, is evident. These results are discussed in terms of a neutron particle contribution and are compared to similar data in lighter Hf nuclei.
ABSTRACT New g-factor measurements by the recoil in vacuum method are discussed. The stable even tin isotopes, neutron-rich 126,128Sn, and tellurium isotopes including neutron-rich semimagic 134Te, have been studied. The experiments were... more
ABSTRACT New g-factor measurements by the recoil in vacuum method are discussed. The stable even tin isotopes, neutron-rich 126,128Sn, and tellurium isotopes including neutron-rich semimagic 134Te, have been studied. The experiments were performed at the Holifield Radioactive Ion Beam Facility (HRIBF) by Coulomb exciting ~ 3 MeV/u beams in inverse kinematics on C and Ti targets, and using the CLARION+HyBall arrays to observe the perturbed particleangular correlations. The measurements, including those on the neutron-rich radioactive beams, have sufficient precision to distinguish between alternative models.
Projectile excitation and the transient-field technique have been used to measure the g factors of the 2^+_1, 2^+2 and 4^+1 states in ^74-82Se in order to determine the interplay between collective and single particle excitations at low... more
Projectile excitation and the transient-field technique have been used to measure the g factors of the 2^+_1, 2^+2 and 4^+1 states in ^74-82Se in order to determine the interplay between collective and single particle excitations at low energies. The states of interest were populated by Coulomb exciting beams of the appropriate isotope by the same natural Si target. The results
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Recently developed techniques combining inverse kinematics Coulomb excitation with traditional transient field techniques have allowed high precision measurements of magnetic moments of low-lying, short-lived nuclear states. Since the... more
Recently developed techniques combining inverse kinematics Coulomb excitation with traditional transient field techniques have allowed high precision measurements of magnetic moments of low-lying, short-lived nuclear states. Since the relative spin change of nuclei is maximum in the low excitation region, the magnetic moments of the 2^+1 and 4^+1 states provide stringent tests of theoretical models. In addition, since there are
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The targets required for the measurement of g factors for short-lived (ps. lifetimes) states of nuclei by the transient field consist of a delicate balance between multiple elements: an excitation layer where the inverse kinematics... more
The targets required for the measurement of g factors for short-lived (ps. lifetimes) states of nuclei by the transient field consist of a delicate balance between multiple elements: an excitation layer where the inverse kinematics Coulomb excitation of the beam occurs, a ferromagnetic layer where the aligned nuclear spins precess, and a stopping layer for the probe ion . The
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The g factor of the 21+ state in 44Ca has been measured using the transient field technique and Coulomb excitation in inverse kinematics. A positive value of g(21+,44Ca)=+0.12±0.05 was deduced. The result suggests the (fp)4ν configuration... more
The g factor of the 21+ state in 44Ca has been measured using the transient field technique and Coulomb excitation in inverse kinematics. A positive value of g(21+,44Ca)=+0.12±0.05 was deduced. The result suggests the (fp)4ν configuration competes with excitations of the 40Ca core. A simple model which considers that the wave function for the 21+ state consists of approximately equal admixtures of spherical four valence neutron configurations and a deformed core configuration accounts for the experimentally observed g factor as well as the previously measured quadrupole moment.
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... GJ KUMBARTZKI, W. KNAUER, G. KROSING, V. MERTENS and PN TANDON1 Inst itut fur Strahlen und Kernphysik, Universitat Bonn, W. Germany J. GERBER and RM FREEMAN Centre des Recherches Nucleaires, Universite Louis Pasteur. ... [21 G. van... more
... GJ KUMBARTZKI, W. KNAUER, G. KROSING, V. MERTENS and PN TANDON1 Inst itut fur Strahlen und Kernphysik, Universitat Bonn, W. Germany J. GERBER and RM FREEMAN Centre des Recherches Nucleaires, Universite Louis Pasteur. ... [21 G. van Middelkoop, lIyp. Tnt. ...
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... G. Martinez-Pinedo, A. Poves, LM Robledo, E. Caurier, F. Nowacki, J. Retamosa, and A. Zuker, Phys. Rev. ... R. Ernst, K.-H. Speidel, O. Kenn, U. Nachum, J. Gerber, P. Maier-Komor, N. Benczer-Koller, G. Jakob, G. Kumbartzki, and L.... more
... G. Martinez-Pinedo, A. Poves, LM Robledo, E. Caurier, F. Nowacki, J. Retamosa, and A. Zuker, Phys. Rev. ... R. Ernst, K.-H. Speidel, O. Kenn, U. Nachum, J. Gerber, P. Maier-Komor, N. Benczer-Koller, G. Jakob, G. Kumbartzki, and L. Zamick (to be published). ...
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We present measurements of the ratio of the proton elastic electromagnetic form factors, μ p G Ep /G Mp . The Jefferson Lab Hall A Focal Plane Polarimeter was used to determine the longitudinal and transverse components of the recoil... more
We present measurements of the ratio of the proton elastic electromagnetic form factors, μ p G Ep /G Mp . The Jefferson Lab Hall A Focal Plane Polarimeter was used to determine the longitudinal and transverse components of the recoil proton polarization in ep elastic scattering; the ...
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The g factor of the 2+1 state in 40Ar has been measured by use of Coulomb excitation in inverse kinematics and the transient magnetic-field technique. The resulting g factor, g(2+1)=-0.015(42), is in reasonable agreement with shell-model... more
The g factor of the 2+1 state in 40Ar has been measured by use of Coulomb excitation in inverse kinematics and the transient magnetic-field technique. The resulting g factor, g(2+1)=-0.015(42), is in reasonable agreement with shell-model calculations within the (full sd)pi(full fp)nu space, without including core excitations. Although highly deformed admixtures in the wave function cannot be completely ruled out,