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Title: {sup 49}Cr: Towards full spectroscopy up to 4 MeV

Abstract

The nucleus {sup 49}Cr has been studied by analyzing {gamma}-{gamma} coincidences in the reaction {sup 46}Ti({alpha},n){sup 49}Cr at the bombarding energy of 12 MeV. The level scheme has been greatly extended at low excitation energy, and several lifetimes have been determined by means of the Doppler shift attenuation method. Shell model calculations in the full pf configuration space reproduce well the negative parity levels. Satisfactory agreement is obtained for positive parity levels by extending the configuration space to include a nucleon-hole in either the 1d{sub 3/2} or 2s{sub 1/2} orbitals. A nearly one-to-one correspondence is found between experimental and theoretical levels up to an excitation energy of 4 MeV. Experimental data and shell model calculations are interpreted in terms of the Nilsson diagram and the particle-rotor model, showing the strongly coupled nature of the bands in this prolate nucleus. Nine values of K{sup {pi}} are proposed for the levels observed in this experiment. As a secondary result, it is shown that the values of the experimental magnetic moments in 1f{sub 7/2} nuclei are well reproduced without quenching the nucleon g factors.

Authors:
; ; ;  [1];  [2]; ; ;  [3];  [4]; ; ; ; ;  [5]
  1. Dipartimento di Fisica dell'Universita and INFN, Sezione di Padova, Padova (Italy)
  2. Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo (Brazil)
  3. Laboratori Nazionali di Legnaro-INFN, Legnaro (Italy)
  4. Departamento de Fisica Teorica, Universidad Autonoma, Cantoblanco, Madrid (Spain)
  5. Institut fuer Kernphysik der Universitaet zu Koeln (Germany)
Publication Date:
OSTI Identifier:
20771264
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 73; Journal Issue: 2; Other Information: DOI: 10.1103/PhysRevC.73.024313; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ALPHA REACTIONS; CHROMIUM 49; COLLECTIVE MODEL; DSA METHOD; ENERGY LEVELS; EXCITATION; LANDE FACTOR; LIFETIME; MEV RANGE; NEUTRONS; NUCLEAR MAGNETIC MOMENTS; PARITY; PARTICLE-CORE COUPLING MODEL; SHELL MODELS; TITANIUM 46 TARGET

Citation Formats

Brandolini, F., Menegazzo, R., Pavan, P., Lenzi, S., Ribas, R.V., Axiotis, M., De Poli, M., Napoli, D., Sanchez-Solano, J., Dewald, A., Fitzler, A., Jessen, K., Kasemann, S., and Brentano, P. von. {sup 49}Cr: Towards full spectroscopy up to 4 MeV. United States: N. p., 2006. Web. doi:10.1103/PhysRevC.73.024313.
Brandolini, F., Menegazzo, R., Pavan, P., Lenzi, S., Ribas, R.V., Axiotis, M., De Poli, M., Napoli, D., Sanchez-Solano, J., Dewald, A., Fitzler, A., Jessen, K., Kasemann, S., & Brentano, P. von. {sup 49}Cr: Towards full spectroscopy up to 4 MeV. United States. doi:10.1103/PhysRevC.73.024313.
Brandolini, F., Menegazzo, R., Pavan, P., Lenzi, S., Ribas, R.V., Axiotis, M., De Poli, M., Napoli, D., Sanchez-Solano, J., Dewald, A., Fitzler, A., Jessen, K., Kasemann, S., and Brentano, P. von. Wed . "{sup 49}Cr: Towards full spectroscopy up to 4 MeV". United States. doi:10.1103/PhysRevC.73.024313.
@article{osti_20771264,
title = {{sup 49}Cr: Towards full spectroscopy up to 4 MeV},
author = {Brandolini, F. and Menegazzo, R. and Pavan, P. and Lenzi, S. and Ribas, R.V. and Axiotis, M. and De Poli, M. and Napoli, D. and Sanchez-Solano, J. and Dewald, A. and Fitzler, A. and Jessen, K. and Kasemann, S. and Brentano, P. von},
abstractNote = {The nucleus {sup 49}Cr has been studied by analyzing {gamma}-{gamma} coincidences in the reaction {sup 46}Ti({alpha},n){sup 49}Cr at the bombarding energy of 12 MeV. The level scheme has been greatly extended at low excitation energy, and several lifetimes have been determined by means of the Doppler shift attenuation method. Shell model calculations in the full pf configuration space reproduce well the negative parity levels. Satisfactory agreement is obtained for positive parity levels by extending the configuration space to include a nucleon-hole in either the 1d{sub 3/2} or 2s{sub 1/2} orbitals. A nearly one-to-one correspondence is found between experimental and theoretical levels up to an excitation energy of 4 MeV. Experimental data and shell model calculations are interpreted in terms of the Nilsson diagram and the particle-rotor model, showing the strongly coupled nature of the bands in this prolate nucleus. Nine values of K{sup {pi}} are proposed for the levels observed in this experiment. As a secondary result, it is shown that the values of the experimental magnetic moments in 1f{sub 7/2} nuclei are well reproduced without quenching the nucleon g factors.},
doi = {10.1103/PhysRevC.73.024313},
journal = {Physical Review. C, Nuclear Physics},
number = 2,
volume = 73,
place = {United States},
year = {Wed Feb 15 00:00:00 EST 2006},
month = {Wed Feb 15 00:00:00 EST 2006}
}
  • High-spin states have been investigated in the mirror pair nuclei {sup 49}Cr (Z=24, N=25) and {sup 49}Mn (Z=25, N=24). Mirror symmetry up to the band termination at about 10.7MeV has been established. A comparison of the corresponding energy levels of the pair shows, for the first time, that the Coulomb energy difference approaches zero as the band termination is approached. This is explained intuitively in terms of a pure f{sub 7/2} shell framework. For {sup 49}Cr, excellent agreement is found between the data and recent full pf-shell calculations. {copyright} {ital 1997} {ital The American Physical Society}
  • The reaction {sup 40}Ca+{sup 12}C at {ital E}{sub Ca}=160 MeV has been used to study high-spin states in the recoil-separated nuclides {sup 49}Cr, {sup 49}V, and {sup 46}Ti. The latter two show distinctive {ital f}{sub 7/2} shell-model behavior up to {ital J}{sup {pi}}=27/2{sup {minus}} and 12{sup +}, respectively, while the first appears to be a collective rotor with a particle alignment at {ital J}{sup {pi}}=17/2{sup {minus}}. Rotorlike bands of {ital sd}-shell origin were seen in {sup 49}V and {sup 46}Ti up to {ital J}{sup {pi}}=11/2{sup +} and 11{sup {minus}}, respectively.
  • By use of a proportional counter, alpha particles were observed from the reactions Al/sup 27/(p, alpha )Mg/sup 24/, resulting in the ground and first excited states of Mg/sup 24/, and Cr/sup 52/ (p, k)V/sup 49/, resulting in the lower three and a few higher states. Excitation curves, measured at a laboratory angle of 50 deg with respect to the bombarding beam, were found to be from l2.7 to l4.1 Mev for Al/sup 27/(p, alpha )Mg/sup 24/, and 9.0 to 14.8 Mev for Cr/sup 52/ (p, alpha )V/sup 4 The former shows a sharp energy dependences while the latter shows amore » fairly smooth structure. Angular distributions were measured at l4.l, 13.0 and 12.8 Mev for Al/sup 27/(p, alpha )Mg/sup 24/, and at 14.2, l3.0, l2.0, ll.0, 10.0, 9.5, and 9.0 Mev for Cr/sup 52/(p, alpha )V/sup 49/. Although the Al/sup 27/(p, alpha /sub 0/)Mg/sup 24/ data can be partially fitted by (j/ sub 2/(Or /sub 0/)!/sup 2/ of Butler's theory. some angular distributiors show strong backward peaking. Interference between various direct interaction processes or between direct interaction and compound nuclear processess or boths are responsible for this reaction. The approximate 90 symmetry of Cr/sup 52/ (p, alpha )V/sup 49/ angular distribution appears to be consistent with the statistical theory of nuclear reactions. The conspicuous forward peak at higher energies, especially at l4.2 Mevs indicates the increasing contribution of direct interaction processes. (auth)« less