The beta-decay energies of103In and104In

Abstract

The/3+ spectra of neutron-deficient nuclei with mass numbers 103 and 104 have been measured, using a semiconductor beta spectrometer. The nuclei were produced by on-line mass separation of reaction products formed by bombarding an enriched Mo target with Ne ions. Values for Q~c have been deduced. The decay energies are in agreement with systematics. The decay of 1~ shows remarkably strong feeding to levels above 5 MeV. In addition, Q~c values for 1~ l~ l~ and l~ have been determined.

Gamow-Teller strength in the ?+ decay of104In

“…To attain this high accuracy, a properly designed correction procedure for effects like back-scattering, bremsstrahlung escape and summation of annihilation quanta is vital [-7, 8]. The correctness of our mass determinations has recently been confirmed by direct mass measurements with an isotope separator [9]: the measured mass differences between ~~ 1~ and ~~ match the values deduced from our QEc measurements [2,6] and by using our precise Q~c values for x~ and a~ a new Qzc value for l~ is obtained (7.92_+0.14 MeV) [9], which is in agreement with our value (7.80_+ 0.25 MeV) [2].…”

“…The results of the fit are given in Table 1. The fit has as input parameters: -the QEc value: 7.89 MeV; a weighted average of the two experimental results [2,9].…”

“…Contamination of the positron spectra by scattered positrons is suppressed by using the signal from the diaphragm made out of scintillator plastic in anti-coincidence mode. Previous measurements [2,6] have shown that the betadecay endpoint energy can be determined accurately, provided the relative feeding of the levels in the daughter nucleus are well known. To attain this high accuracy, a properly designed correction procedure for effects like back-scattering, bremsstrahlung escape and summation of annihilation quanta is vital [-7, 8].…”

“…In this article, we report on a different approach to evaluate singles positron spectra: by using the measured QEc value [2,93 and the known response function of the beta detector, it is possible to extract in an unique way the gross structure of the/3-strength function; a similar kind of information is obtained with the total absorption gamma spectroscopy method [14]. While the total absorption gamma spectroscopy measures directly the fi++ EC intensity per level interval by summing up all emitted 7 radiation (4re-?…”

“…This anomaly has recently been solved by our group. The beta-decay energies of ~~ and 1~ have been remeasured [2] and a detailed decay scheme of l~ has been constructed [3]. A remarkably strong feeding to levels above 5 MeV in 1~ and the subsequent 7 decay of statistical character makes standard spectroscopic methods in this region unreliable: it is impossible to extract the //-strength function out of the intensity balance of the discrete 7 rays feeding and deexciting a certain level.…”