The role of angular-momentum removal in photonuclear reactions as deduced from the isomeric ratios for and

Abstract

A model interpretation of isomeric ratios for 117m,g In and 120m,g Sb produced in the reactions 118 Sn(γ , p), 119 Sn(γ , np), 121 Sb(γ , α), nat Sb(γ , α2n), 121 Sb(γ , n) and nat Sb(γ , 3n) is presented. The experimental isomeric ratios were obtained using bremsstrahlung radiation with end-point energies of 18 and 43 MeV. The calculations were performed by means of the well known code STAPRE and the new code COMPLET. Angular-momentum removal in preequilibrium emission was found to be much more important for the observed isomeric ratios than subsequent compound-nucleus evaporation.

The Study of Isomeric Ratios in Photonuclear Reactions Forming High Spin Isomers in the Giant Dipole Resonance Region

“…The isomeric ratios furnish valuable information about the energy level structure of nuclei and the nuclear reaction mechanism involved [1][2][3][4][5]. This quantity depends on the spin of target nucleus and the intake angular momentum determined by the mass and the energy of projectile particles.…”

$^{197}$Au($γ,\,xn;\,x\,=\,1\thicksim7$) Reaction Measurements using Laser-Driven Ultra-Bright Ultra-Fast Bremsstrahlung $γ$-Ray

“…Photonuclear reaction cross sections and their isomeric yield ratios are very important in the field of nuclear structures, nuclear reaction mechanisms, and nuclear astrophysics [1][2][3]. The isomeric yield ratio of a nuclear reaction depends on the projectile particles and the spins of both target and daughter nuclei, which is used as a good test for nuclear structure theories and nuclear reaction models [1,2,4,5]. In nuclear astrophysics, there are 30-35 proton-rich nuclei (p-nuclei) which can not be produced by neutron-capture processes (s-process and rprocess) [6][7][8].…”

Excitation of 117In 1/2- isomeric state in (γ,p) reactions

“…За останнi роки значення iзомерних вiдношень для цiєї реакцiї опублiкованi в низцi робiт [2][3][4][5][6][7][8][9][10] (значення наведенi в Таблицi 1), але всi вони отриманi в окремих енерґетичних точках, на установках з рiзними характеристиками i, вiдповiдно, з рiзними систематичними похибками. Так, у працях [4,5] опромiнення проводили на бетатронах Б-25/30 i СБ-50 вiдповiдно, в iнших використовували мiкротрони й лiнiйнi прискорювачi.…”

“…Тривалiсть опромiнення t irr була в межах 20-50 хв. Наведену активнiсть вимiрювали гамма-спектрометром з Ge(Li) детектором об'ємом 100 см 3 Визначали iзомернi вiдношення за методикою, описаною в статтi [12]. Iзомерне вiдношення d = Y m /Y n розраховували за формулою [13]:…”