Zakład Doświadczalnej Fizyki Komputerowej » beta decay

2011: Half-life of the β decay 115In(9/2+)→115Sn(3/2+)

misiaszek — Thu, 03 Nov 2011 08:48:47 +0000

Phys. Rev. C 84, 044605 (2011)

Erica Andreotti,1, Mikael Hult,1, Raquel González de Orduña,1, Gerd Marissens,1, J. S. Elisabeth Wieslander,1, and Marcin Misiaszek,2

¹EC-JRC-IRMM, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel, Belgium
²M. Smoluchowski Institute of Physics, Jagiellonian University, ulica Reymonta 4, PL-30-059 Krakow, Poland

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Abstract

The half-life of the rare β⁻ decay of ¹¹⁵In (9/2+) to ¹¹⁵Sn (3/2+) was determined by measuring the subsequent 497.334(22) keV γ-ray emission in a high-purity indium sample. The measurements were carried out by means of ultralow-level γ-ray spectrometry in the HADES underground laboratory, using three different high-purity germanium detectors. The value of the partial half-life for this low-Q_β⁻ transition was measured to be 4.3(5) × 10²⁰ yr.

2009: Smallest Known Q Value of Any Nuclear Decay: The Rare beta- Decay of 115In–>115Sn

admin — Wed, 21 Oct 2009 07:53:02 +0000

Phys. Rev. Lett. 103, 122501 (2009)

J. S. E. Wieslander,1,2 J. Suhonen,2 T. Eronen,2 M. Hult,1 V.-V. Elomaa,2 A. Jokinen,2 G. Marissens, M. Misiaszek,3 M. T. Mustonen,2 S. Rahaman,2 C. Weber,2 and J. Äystö2

1)EC-JRC-IRMM, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel, Belgium
2)Department of Physics, P.O. Box 35 (YFL), FIN-40014 University of Jyväskylä, Finland
3)Marian Smoluchowski Institute of Physics, Jagiellonian University, ul. Reymonta 4, 30-059 Krakow, Poland

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Abstract

The ground-state-to-ground-state Qbeta- value of 115In was determined to 497.68(17) keV using a high-precision Penning trap facility at the University of Jyväskylä, Finland. From this, a Qbeta- value of 0.35(17) keV was obtained for the rare beta- decay to the first excited state of 115Sn at 497.334(22) keV. The partial half-life was determined to 4.1(6)×1020 yr using ultra low-background gamma-ray spectrometry in an underground laboratory. Theoretical modeling of this 2nd-forbidden unique beta- transition was also undertaken and resulted in Qbeta-=57_-12⁺¹⁹ eV using the measured half-life. The discrepancy between theory and experiment could be attributed to atomic effects enhanced by the low Q value. The present study implies that this transition has the lowest Q value of any known nuclear beta decay.

2009: Search for the radioactivity of 180mTa using an underground HPGe sandwich spectrometer

admin — Wed, 21 Oct 2009 08:16:58 +0000

Applied Radiation and Isotopes
Volume 67, Issue 5, May 2009, Pages 918-921

Mikael Hult a, J.S. Elisabeth Wieslander a, c, Gerd Marissens a, Joël Gasparro a, Uwe Wätjen a and Marcin Misiaszek b

a) European Commission, Joint Research Centre, Institute for Reference Materials and Measurements, Retieseweg 111, B-2440 Geel, Belgium
b) M. Smoluchowski Institute of Physics, Jagiellonian University, ul. Reymona 4, 30-059 Krakow, Poland
c) Department of Physics, P.O. Box 35 (YFL), FIN-40014 University of Jyväskylä, Finland

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Abstract

The radioactivity of 180mTa has never been detected. The present attempt to detect it was carried out using a newly developed HPGe sandwich spectrometer installed 500 m water equivalent underground in the HADES laboratory. The sample consisted of 6 discs of tantalum of natural isotopic composition with a total mass of 1500 g and a total mass for 180Ta of 180 mg. The sample was measured for 68 days and the resulting lower bound for the half-life of 180mTa was 2.0×1016 y, which is a factor of 2.8 higher than the previous highest value