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Title: Measurement of the p to s Wave Branching Ratio of {sup 187}Re {beta} Decay from Beta Environmental Fine Structure

Abstract

The mixed occurrence of s-wave and p-wave contributions in a first forbidden unique Gamow-Teller {beta} decay has been investigated for the first time by measuring the beta environmental fine structure (BEFS) in a {sup 187}Re crystalline compound. The experiment has been carried out with an array of eight AgReO{sub 4} thermal detectors operating at a temperature of {approx}100 mK. A fit of the observed BEFS spectrum indicates the p-wave electron emission as the dominant channel. The complete understanding of the BEFS distortion of the {sup 187}Re {beta} decay spectrum is crucial for future experiments aiming at the precise calorimetric measurement of the antineutrino mass.

Authors:
; ; ; ; ; ; ; ; ; ; ;  [1];  [2];  [3]; ;  [4];  [5]
  1. Dipartimento di Fisica dell'Universita di Milano-Bicocca and Sezione di Milano dell'INFN, Milan (Italy)
  2. Dipartimento di Scienza dei Materiali dell'Universita di Milano-Bicocca and Sezione di Milano dell'INFN, Milan (Italy)
  3. Dipartimento di Fisica dell'Universita dell'Aquila, Coppito (AQ) (Italy)
  4. Dipartimento di Fisica dell'Universita dell'Insubria, Como (Italy) and Sezione di Milano dell'INFN (Italy)
  5. ITC-IRST and Gruppo Collegato di Trento dell'INFN, Povo (Tunisia) (Italy)
Publication Date:
OSTI Identifier:
20778538
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review Letters; Journal Volume: 96; Journal Issue: 4; Other Information: DOI: 10.1103/PhysRevLett.96.042503; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ANTINEUTRINOS; BETA DECAY; BRANCHING RATIO; ELECTRON EMISSION; FINE STRUCTURE; GAMOW-TELLER RULES; MASS; P WAVES; RHENIUM 187; S WAVES

Citation Formats

Arnaboldi, C., Brofferio, C., Capelli, S., Capozzi, F., Cremonesi, O., Fiorini, E., Nucciotti, A., Pavan, M., Pessina, G., Pirro, S., Previtali, E., Sisti, M., Benedek, G., Filipponi, A., Giuliani, A., Pedretti, M., and Monfardini, A. Measurement of the p to s Wave Branching Ratio of {sup 187}Re {beta} Decay from Beta Environmental Fine Structure. United States: N. p., 2006. Web. doi:10.1103/PHYSREVLETT.96.0.
Arnaboldi, C., Brofferio, C., Capelli, S., Capozzi, F., Cremonesi, O., Fiorini, E., Nucciotti, A., Pavan, M., Pessina, G., Pirro, S., Previtali, E., Sisti, M., Benedek, G., Filipponi, A., Giuliani, A., Pedretti, M., & Monfardini, A. Measurement of the p to s Wave Branching Ratio of {sup 187}Re {beta} Decay from Beta Environmental Fine Structure. United States. doi:10.1103/PHYSREVLETT.96.0.
Arnaboldi, C., Brofferio, C., Capelli, S., Capozzi, F., Cremonesi, O., Fiorini, E., Nucciotti, A., Pavan, M., Pessina, G., Pirro, S., Previtali, E., Sisti, M., Benedek, G., Filipponi, A., Giuliani, A., Pedretti, M., and Monfardini, A. Fri . "Measurement of the p to s Wave Branching Ratio of {sup 187}Re {beta} Decay from Beta Environmental Fine Structure". United States. doi:10.1103/PHYSREVLETT.96.0.
@article{osti_20778538,
title = {Measurement of the p to s Wave Branching Ratio of {sup 187}Re {beta} Decay from Beta Environmental Fine Structure},
author = {Arnaboldi, C. and Brofferio, C. and Capelli, S. and Capozzi, F. and Cremonesi, O. and Fiorini, E. and Nucciotti, A. and Pavan, M. and Pessina, G. and Pirro, S. and Previtali, E. and Sisti, M. and Benedek, G. and Filipponi, A. and Giuliani, A. and Pedretti, M. and Monfardini, A.},
abstractNote = {The mixed occurrence of s-wave and p-wave contributions in a first forbidden unique Gamow-Teller {beta} decay has been investigated for the first time by measuring the beta environmental fine structure (BEFS) in a {sup 187}Re crystalline compound. The experiment has been carried out with an array of eight AgReO{sub 4} thermal detectors operating at a temperature of {approx}100 mK. A fit of the observed BEFS spectrum indicates the p-wave electron emission as the dominant channel. The complete understanding of the BEFS distortion of the {sup 187}Re {beta} decay spectrum is crucial for future experiments aiming at the precise calorimetric measurement of the antineutrino mass.},
doi = {10.1103/PHYSREVLETT.96.0},
journal = {Physical Review Letters},
number = 4,
volume = 96,
place = {United States},
year = {Fri Feb 03 00:00:00 EST 2006},
month = {Fri Feb 03 00:00:00 EST 2006}
}
  • Since the ..beta.. decay of /sup 187/Re is first-forbidden unique, the ratio rho of bound-state to continuum ..beta.. decay of /sup 187/Re reduces to a problem in atomic physics. A knowledge of rho is required if one is to connect the experimentally determined value of the rate of continuum decay to a value of the half-life T/sub 1/2/ for the ..beta.. decay of /sup 187/Re. The value of T/sub 1/2/ plays a significant role in the use of the geochemically determined ratio of /sup 187/Os to /sup 187/Re in the estimation of the age of our galaxy. Our results formore » rho, based on the Hartree-Fock-Dirac single-configuration and the multiconfiguration Dirac-Fock approximations strengthen the conclusion of Williams, Fowler, and Koonin (Astrophys. J. 281, 363 (1984)) based on a modified Thomas-Fermi model, that rho is only of the order of 1%. We also include a few values of the rate for a process first considered by Perrone (Ph.D. thesis, Rice University (1971)), the bound-state ..beta.. decay of a bare /sup 187/Re nucleus. (Since the mass of the /sup 187/Re nucleus is less than the sum of the masses of its daughter nucleus /sup 187/Os and of an electron, continuum decay of a bare /sup 187/Re nucleus is forbidden; neutral /sup 187/Re can ..beta.. decay only because of the greater binding energy of the electrons of /sup 187/Os than of /sup 187/Re.)« less
  • The /sup 16/N(2/sup -/,g.s.)..-->.. /sup 16/O(0 /sup +/,g.s.)+e/sup -/+nu-bar/sub e/ branching ratio is remeasured. A flatfield magnetic spectrometer, instrumented with a multiwire position-sensitive proportional detector, is used. A value for the branching ratio GAMMA/sub ..beta../(2/sup -/..-->..0/sup +/)/GAMMA/sub ..beta../(2/sup -/ ) = 0.2811 +- 0.0064 is determined. Combining this result with another recent determination produces a best value for this branching ratio. This in turn allows a more precise determination of the beta-decay rate (..lambda../sub ..beta../) for the process /sup 16/N(0/sup -/, 120 keV)..-->.. /sup 16/O(0/sup +/,g.s.)+e/sup -/ +nu-bar/sub e/. A value ..lambda../sub ..beta../(0/sup -/..-->..0/sup +/) = 0.489 +- 0. 020more » sec/sup -1/ is obtained, which agrees with calculation only when pion exchange currents are included in the nucleon axial current.« less
  • We observed the bound-state {beta}{sup {minus}} decay of fully ionized {sup 187}Re nuclei circulating in a storage ring. With two independent methods the time dependent growth of hydrogenlike {sup 187}Os ions has been measured and a half-life of 32.9{plus_minus}2.0 yr for bare {sup 187}Re nuclei could be determined, to be compared with 42Gyr for neutral {sup 187}Re atoms. With the resulting log{ital ft} value of 7.87{plus_minus}0.03 the half-life of {sup 187}Re ions in any ionization state can be calculated. Thus one can correct the {sup 187}Re-{sup 187}Os galactic chronometer calibration, by taking account of the {beta}{sup {minus}} decay enhancement inmore » stellar interiors, which will lead to a more accurate estimate of the galactic age. {copyright} {ital 1996 The American Physical Society.}« less
  • The ratio of the neutron capture cross sections for /sup 186/Os and /sup 187/Os was measured at the 25-keV iron-filtered neutron beam facility of a 10-MW reactor. A value of 0.41 +- 0.04 was obtained. On the bases of this ratio, the age of the universe was determined via the Re--Os ..beta..-decay clock to be approximately 19 x 10/sup 9/ years. (AIP)
  • The decay {sup 187}Re(5/2{sup +}) {r_arrow} {sup 187}Os{1/2}{sup -} + e{sup -} + {anti v}{sub e}, Q{sub {Beta}-}=2.6 keV, t{sub {1/2}} = 4.3 x 10{sup 10} yrs, may be studied in a superconducting Re absorber operating at temperatures of {approximately} 0.1 Kelvin. The temperature transient, in principle, can provide a high resolution ({approximately} 5 eV FWHM) measure of the total energy not given to the {anti v}{sub e} of individual beta decays. The technique avoids the practical problems of energy loss in the source, slit scattering, and variation in detection efficiency as well as the theoretical question of final states.more » However, the necessity of viewing the entire spectrum raises the question of the statistical accuracy achievable in a practical experiment. By Monte Carlo study, including the effects of pileup and background and the measurement of the resolution function, we demonstrate that, theoretically, a single device can reach a precision of 60 eV{sup 2} (1 {sigma}) or 10 eV (95% C.L.), assuming a central value of zero, in 50 days and that 16 such detectors could reach a 5 eV limit in the same time.« less