New limits on double-beta decay of $$^{190}$$Pt and $$^{198}$$Pt

A search for double-beta decay of $$^{190}$$ 190 Pt and $$^{198}$$ 198 Pt with emission of $$\gamma $$ γ -ray quanta was realized at the HADES underground laboratory with a 148 g platinum sample measured by two ultralow-background HPGe detectors over 8946 h. The isotopic composition of the platinum sample has been measured with high precision using inductively coupled plasma mass spectrometry. New lower limits for the half-lives of $$^{190}$$ 190 Pt relative to different channels and modes of the decays were set on the level of $$\lim T_{1/2}\sim 10^{14}$$ lim T 1 / 2 ∼ 10 14 –$$10^{16}$$ 10 16 year. A possible exact resonant $$0\nu KN$$ 0 ν K N transition to the 1,2 1326.9 keV level of $$^{190}$$ 190 Os is limited for the first time as $$T_{1/2} \ge 2.5 \times 10^{16}$$ T 1 / 2 ≥ 2.5 × 10 16 year. A new lower limit on the double-beta decay of $$^{198}$$ 198 Pt to the first excited level of $$^{198}$$ 198 Hg was set as $$T_{1/2} \ge 3.2\times 10^{19}$$ T 1 / 2 ≥ 3.2 × 10 19 year, one order of magnitude higher than the limit obtained in the previous experiment.

β-Delayed γ Emissions of 26P and Its Mirror Asymmetry

The study of the origin of asymmetries in mirror β decay is extremely important to understand the fundamental nuclear force and the nuclear structure. The experiment was performed at the National Laboratory of Heavy Ion Research Facility in Lanzhou (HIRFL) to measure the β-delayed γ rays of 26P by silicon array and Clover-type high-purity Germanium (HPGe) detectors. Combining with results from the β decay of 26P and its mirror nucleus 26Na, the mirror asymmetry parameter δ ( ≡ft+/ft−− 1) was determined to be 46(13)% for the transition feeding the first excited state in the daughter nucleus. Our independent results support the conclusion that the large mirror asymmetry is close to the proton halo structure in 26P.

New method for the production of thin and stable, segmented n$$+$$ contacts in HPGe detectors

The realization of pulsed-laser diffused, thin n$$+$$ + contacts on high purity germanium (HPGe) and their successful segmentation is described. The contacts have been obtained by a laser-induced diffusion of Sb atoms, deposited by sputtering on Ge surface, and then segmented by means of a photolithographic technique. Three small prototypes of gamma ray detectors have been implemented, using the same n$$+$$ + contact (laser diffused Sb) but with three different geometries and a B implanted p$$+$$ + contact. Electrical and detection properties of the prototypes have been characterized, showing low leakage currents and good spectroscopy data with different gamma-ray sources. The stability of the detector performance has also been tested subjecting one of the prototypes to a typical annealing treatment.

Application of a new in situ calibration technique for gamma spectrometry and comparison of in situ and laboratory measurements

In situ gamma ray spectrometry was developed to quickly measure large areas of land following nuclear accidents. However, a proper calibration of detectors for in situ measurements is a long and complicated process. One tool designed to make this calibration quick is the InSiCal software. We compared 5,000 s in situ measurements with two different HPGe detectors calibrated using the InSiCal software and laboratory measurements of samples collected at the same locations. Our findings suggest that in situ gamma spectrometry using InSiCal software can provide reasonably accurate data, but some improvements are needed.