Cryogenic micro-calorimeter measurement of the {sup 107}Pd {Beta} decay spectrum
We are studying the decay {sup 107}Pd(5/2{sup +}) {r_arrow} {sup 107}Ag({1/2}{sup -}) e{sup -} + {anti v}{sub e}, Q{sub {Beta}-} =37.5 keV, with sources encapsulated in a superconducting Sn absorber operating at a temperature of 0.1 Kelvin. A neutron transmutation-doped germanium thermistor measures the temperature transient ({approximately} 5 msec long) caused by individual beta decays. Pulses are digitally record at a rate of 4 decays per second. We determine the total energy not given to the {anti v}{sub e} with a resolution full-width-half-maximum of {approximately} 0.5 keV and a threshold of {approximately}5 keV. The response function of the device is determined from measurements of the mono-energetic electron capture and internal conversion source {sup 109}Cd, both simultaneously with the beta spectrum and separately. We find the endpoint of the unique first-forbidden decay to be 37-5 {+-} 0.1 keV, 4.5 keV higher than the mass tables, 33.0 {+-} 3.1 keV. Results of 4 weeks of data taking from threshold to above the new endpoint will be presented, allowing comparison to the unique first-forbidden shape and the atomic exchange correction. In addition, a test for 17 keV neutrino admixture is being made and results will be presented.
- OSTI ID:
- 387249
- Report Number(s):
- CONF-931044--
- Journal Information:
- Bulletin of the American Physical Society, Journal Name: Bulletin of the American Physical Society Journal Issue: 9 Vol. 38; ISSN 0003-0503; ISSN BAPSA6
- Country of Publication:
- United States
- Language:
- English
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