Y-89 MACS case

The MACS for Y-89 is fully determined by the resolved resonance region (neutron energies up to 100 keV), for kT = 5 keV. At higher temperatures, the MACS fraction covers up to 90% at kT = 30 keV, and up to 40% for kT = 100 keV. Here below, these estimates are shown for the capture cross section taken from the evaluated nuclear data file JENDL-4.0.

The MACS derived from the resolved resonance region (data file from 17-JAN-2022), measured at n_TOF, are given here below.

# kT in keV, MACS-kT in mb
# n_TOF-res    : eperimental kernel data file
# thermal      : 1128 +/- 20 mb (Mughabghab, 2018)
# DRC          : p-wave component only
# total        : n_TOF-res (E <   94 keV) + b80-he (E >   94 keV) + ther(1/v) + DRC
# ----- uncertainties -----
# E <   94 keV           :  5% from kernel + BG + norm
# therm(1/v)             :  2% (from thermal)
# E >   94               : 10% assumed
#  kT      T6      total   unc[%] n_TOF-res   unc[%]  ther(1/v)       DRC     j40-all   j40-res    j40-he     b80-all   b80-res    b80-he     j33-all   j33-res    j33-he
  5.0     58.0     72.27      4.8     69.68      3.5       2.54       0.00      72.14     72.93      0.00       71.67     72.57      0.05       71.69     72.57      0.00
  8.0     92.8     50.27      4.7     47.46      2.4       2.01       0.00      49.68     50.22      0.00       50.72     50.57      0.80       50.73     50.57      0.00
 10.0    116.0     43.23      4.6     39.65      2.0       1.79       0.00      42.04     42.48      0.01       43.82     42.57      1.78       43.83     42.57      0.02
 15.0    174.1     34.68      4.3     28.72      1.4       1.46       0.00      31.54     31.72      0.16       34.07     29.95      4.49       34.08     29.95      0.23
 20.0    232.1     30.60      4.3     22.78      1.1       1.27       0.00      26.04     25.72      0.59       28.49     22.22      6.55       28.50     22.22      0.75
 23.0    266.9     28.89      4.4     20.26      1.0       1.18       0.00      23.82     23.10      0.97       26.12     18.90      7.45       26.12     18.90      1.17
 25.0    290.1     27.92      4.4     18.84      0.9       1.13       0.00      22.62     21.60      1.26       24.80     17.07      7.94       24.81     17.07      1.48
 30.0    348.1     25.87      4.6     15.95      0.8       1.04       0.00      20.31     18.46      2.05       22.20     13.48      8.89       22.21     13.48      2.28
 35.0    406.2     24.20      4.9     13.70      0.7       0.96       0.00      18.65     15.97      2.85       20.30     10.90      9.54       20.31     10.90      3.08
 40.0    464.2     22.79      5.1     11.91      0.6       0.90       0.00      17.39     13.94      3.60       18.86      8.98      9.99       18.86      8.98      3.83
 45.0    522.2     21.58      5.4     10.44      0.5       0.85       0.00      16.41     12.27      4.27       17.73      7.52     10.30       17.74      7.52      4.51
 50.0    580.2     20.54      5.6      9.22      0.5       0.80       0.00      15.61     10.87      4.86       16.83      6.39     10.51       16.83      6.39      5.10
 55.0    638.3     19.62      5.8      8.20      0.4       0.77       0.00      14.95      9.68      5.37       16.08      5.49     10.65       16.08      5.49      5.62
 60.0    696.3     18.81      6.0      7.34      0.4       0.73       0.00      14.38      8.68      5.80       15.45      4.77     10.74       15.45      4.77      6.06
 70.0    812.3     17.43      6.4      5.97      0.3       0.68       0.00      13.47      7.08      6.47       14.44      3.69     10.79       14.44      3.69      6.75
 80.0    928.4     16.32      6.8      4.95      0.2       0.63       0.00      12.75      5.88      6.94       13.65      2.94     10.74       13.65      2.94      7.26
 90.0   1044.4     15.41      7.0      4.16      0.2       0.60       0.00      12.17      4.95      7.27       13.02      2.40     10.65       13.02      2.40      7.62
100.0   1160.5     14.65      7.3      3.55      0.2       0.57       0.00      11.69      4.23      7.51       12.50      1.99     10.53       12.50      1.99      7.87

MACS plot and hi-res table

A comparison with the KADONIS-1.0 database and with the values available in the ENDF/B-VIII.0 (j80) and JENDL-4.0 (j40) libraries is shown in the figure below. A table with a much finer temperature grid is available here.

MACS vs temperature

DRC contribution?

DRC contribution to the capture cross section has been evaluated. The ground (2-) and first excited state (3- at 0.202 MeV) of ⁹⁰Y have a strong | ⁸⁹Y(1/2-) > ⊗ | 2d_5/2 > configuration, with their spectroscopic strength of the order of 50% each (see ENDSF). The second (0- at 1.21 MeV) and third (1- at 1.37 MeV) excited states have, in turn, a | ⁸⁹Y(1/2-) > ⊗ | 3s_1/2 > configuration, also with approximately 50% spectroscopic strength each. The p-wave DRC component to the MACS turns out to be less than 1 mb, for the whole range of temperatures in consideration here. Therefore, no DRC component has been added to the MACS.