Showing papers by "Petr Vogel published in 1991"

Response of 127I to solar neutrinos.

Abstract: We use a configuration-mixing quasiparticle Tamm-Dancoff approximation to calculate the expected event rate for an 127I solar neutrino detector. Our cross section for 8B solar neutrinos is 2.2×10-42 cm2 [corresponding to about 13 solar neutrino units (SNU) in the standard solar model], a factor of more than 3 below an estimate by Haxton. This value may increase by about 30% when quadrupole correlations are included. The cross section for ‘‘Be neutrinos is 2.0×10-45 cm2 (9.4 SNU), in agreement with a calculation by Dellagiacoma and Iachello. The total event rate per nucleus from all solar neutrinos is about 3 times that in 37Cl.

Double beta decay and theory of nuclear structure

Abstract: The successes and difficulties of the QRPA are discussed first. In particular, the sensitivity of the double beta decay matrix elements on the choice of the proper nucleon-nucleon interaction and the corresponding set of single particle energies is described. The generalized seniority shell model is discussed. It is shown that it leads to results similar to the results of QRPA, avoiding, however, some of its problem. The problem of the isospin nonconservation and spurious center-of-mass motion is briefly described.

Extent of simultaneous parity and time violation in 182W.

Abstract: In order to relate nuclear gamma-ray distributions to the fundamental parity-time- (PT-) and parity- (P-) violating meson-nucleon interaction, we analyze the case of the mixed (E1,M2,E3) 1189-keV gamma ray in 182W which is populated in the decay of cryogenically oriented 182Ta. Within the framework of the quasiparticle random-phase approximation we calculate the value of the complex ‘‘irregular’’ mixing ratio ɛ(E2¯/M2) for this transition. We estimate that this mixing ratio will have a P-violating real part of ‖ɛ‖cosη≃5×10-5 which implies an observable forward-backward asymmetry (〈J〉⋅k) in the 1189-keV gamma-ray directional distribution of OP≃2×10^-5 at 10 mK. For the PT-violating imaginary part we find ‖ɛ‖sinη≃200g πNN(I=1), where g πNN(I=1) is the strength of the isovector PT-violating pion-nucleon coupling. An upper limit to this constant of ≲3×10^-10 may be obtained from the electric dipole moment of the neutron. Whence we conclude that at 10 mK one needs to measure the PT-violating correlation (〈J〉⋅k2)(〈J〉⋅k1×k2) to an accuracy of OPT≲2×10^-8 in order to improve the limit on g πNN(I=1) set by the neutron electric dipole moment.