C. Galbiati, M. Misiaszek and N. Rossi

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http://dx.doi.org/10.1140/epja/i2016-16086-1

Abstract

In this report we describe the unique capabilities of the α/β discrimination of the Borexino experiment. This capability is the direct result of years of development aimed at the design of an experiment that could withstand contamination from α-emitting nuclides. The combination of the excellent α/β discrimination and of the excellent radiopurity of the detector permitted to extract information on the solar neutrino interactions in Borexino without interference from α particles.

N. Frodyma, K. Pelczar,  M. Wójcik

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http://dx.doi.org/10.1016/j.nima.2014.01.039

Abstract

The results of alpha spectrometric measurements of the activity of ²²²Rn daughters dissolved in liquefied nitrogen are presented. A direct detection method of ionized alpha-emitters from the ²²²Rn decay chain (²¹⁴Po and ²¹⁸Po) in a cryogenic liquid in the presence of an external electric field is shown. Properties of the radioactive ions are derived from a proposed model of ion production and transport in the cryogenic liquid. Ionic life-time of the ions was found to be on the order of 10 s in liquid nitrogen (4.0 purity class). The presence of positive and negative ions was observed.

Applied Radiation and Isotopes 81 (2013) 146–150

M. Misiaszek a), K. Pelczar a), M. Wójcik a), G. Zuzel a) & M. Laubenstein b)

a) M. Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, PL-30-059 Kraków, Poland
b) Laboratori Nazionali del Gran Sasso, INFN, S.S. 17/bis km 18+910, Assergi(AQ), I-67100 Italy

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http://dx.doi.org/10.1016/j.apradiso.2013.03.006

Abstract

Results of alpha spectrometric measurements deep underground and above ground with and without active veto show that the underground measurement of thick samples is the most sensitive method due to significant reduction of the muon-induced background. In addition, the polonium diffusion for some samples requires an appropriate selection of an energy region in the registered spectrum. On the basis of computer simulations the best counting conditions are selected for a thick lead sample in order to optimize the detection limit.

Volume 676, 1 June 2012, Pages 140–148

G. Zuzel a), M. Wójcik b)

a) Max Planck Institute for Nuclear Physics, P.O. Box 103 980, D-69029 Heidelberg, Germany
b) M. Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, PL-30-059 Kraków, Poland

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http://www.sciencedirect.com/science/article/pii/S0168900211022522

Abstract

Removal of the long-lived 222Rn daughters from copper and stainless steel surfaces was investigated. Etching and electropolishing were applied to discs exposed earlier to a strong radon source for 210Pb, 210Bi and 210Po deposition. Cleaning efficiency for 210Pb was tested with a n-type high purity germanium spectrometer, for 210Bi a beta spectrometer and for 210Po an alpha spectrometer was used. According to the performed measurements electropolishing removes very effectively all the isotopes from copper and stainless steel. Copper etching reduces efficiently lead and bismuth however for polonium the effect is negligible because of its fast re-deposition. For stainless steel, etching is much more effective compared to copper and it also works for 210Po.

Volume 676, 1 June 2012, Pages 149–154

G. Zuzel a), M. Wójcik b), B. Majorovits c), M.O. Lampert d), P. Wendling d)

a) Max Planck Institute for Nuclear Physics, P.O. Box 103 980, D-69029 Heidelberg, Germany
b) M. Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, PL-30-059 Kraków, Poland
c) Max-Planck-Institut für Physik, Föhringer Ring 6, 80805 München, Germany
d) Canberra-France, 1 Chemin de la Roseraie, B.P. 311, 67834 Tanneries Cedex, France

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http://www.sciencedirect.com/science/article/pii/S0168900211021929

Abstract

Removal and deposition efficiencies of the long-lived 222Rn daughters during etching from and onto surfaces of standard and high purity germanium were investigated. The standard etching procedure of Canberra–France used during production of high purity n-type germanium diodes was applied to germanium discs, which have been exposed earlier to a strong radon source for deposition of its progenies. An uncontaminated sample was etched in a solution containing 210Pb, 210Bi and 210Po. All isotopes were measured before and after etching with appropriate detectors. In contrast to copper and stainless steel, they were removed from germanium very efficiently. However, the reverse process was also observed. Considerable amounts of radioactive lead, bismuth and polonium isotopes present initially in the artificially polluted etchant were transferred to the clean high purity surface during processing of the sample.