Experimentally constrained(p,γ)Y89and(n,γ)

Abstract

The nuclear level density and the γ-ray strength function have been extracted for 89 Y, using the Oslo Method on 89 Y(p, p γ) 89 Y coincidence data. The γ-ray strength function displays a low-energy enhancement consistent with previous observations in this mass region ( 93−98 Mo). Shell-model calculations give support that the observed enhancement is due to strong, low-energy M1 transitions at high excitation energies.The data were further used as input for calculations of the 88 Sr(p, γ) 89 Y and 88 Y(n, γ) 89 Y cross sections with the TALYS reaction code. Comparison with cross-section data, where available, as well as with values from the BRUSLIB library, shows a satisfying agreement.

Indirect $$(n, \gamma )^{91,92}$$ Zr Cross Section Measurements for the s-Process

“…Finally, our measurements at the lowest energies (i.e., around 2 MeV) also suggest the presence of a low-energy enhancement (the so-called upbend) that has been suggested by shell-model calculations to be of M1 nature [40,41]. For nuclei studied in this mass region with the Oslo method, we find a low-energy enhancement (upbend) of the γ SF [42][43][44][45][46]. The upbend has also been verified for 96 Mo using another technique [47].…”

“…The main uncertainties in the present analysis stem from the E1-M1 decomposition as well as the normalization of the experimental γ SF. Note that the intrinsic model uncertainties, using all available NLD and γ SF models in TALYS, yield a factor ∼10 between the minimum and maximum (n,γ ) cross sections in this mass region [43]. Thus, although our indirect method gives a rather large error band, it is still a significant improvement compared to the range of possible values from the unconstrained model predictions.…”

Low energy magnetic radiation enhancement in thef7/2shell

“…In [23,25] it was found that the E2 transitions are of minor importance whereas the dipole transitions dominate in the low-E γ enhancement region. The first theoretical evidence of the strong enhancement at low E γ came from the shell model calculations of B(M1) values for 90 Zr, 94−96 Mo [22] and 56,57 Fe [27] where the calculated B(M1) and the γSF showed large values for low E γ .…”

“…In the last decade things have become more complicated, since measurements of the γSF [10,[14][15][16][17][18][19][20][21][22][23][24][25][26] have revealed a newly observed minimum around E γ ≃ 2 − 4 MeV, so besides the high E γ enhancement, there is also a low E γ enhancement. The first attempts to understand the low-E γ enhancement [14,15,17] used the KMF model to describe the GDR; the contribution of the giant magnetic dipole resonance to the total γSF is fitted by a Lorentzian, similarly to the E2 resonance, while the low-E γ region is described by a separate term that has a power-law parametrization.…”

Nuclear level densities and γ -ray strength functions of Ta180,181,182

“…Hence, NLD and γ SF are nuclear properties of significance to nucleosynthesis [7] and calculations have shown that relative small changes to the overall shape of the γ SF, such as a pygmy resonance, can have an order-of-magnitude effect on the rate of elemental formation [8]. It has been shown that measured statistical properties can reliably be used to reproduce capture cross sections that were measured using other techniques [9][10][11], although further validations are needed across the nuclear chart. Additionally, NLD and γ SF can also be relevant to the design of existing and future nuclear power reactors, where simulations depend on such nuclear data [1].…”