A. Maulik

Calibration of a solid state nuclear track detector (SSNTD) with high detection threshold to search for rare events in cosmic rays

Abstract We have investigated a commercially available polymer for its suitability as a solid state nuclear track detector (SSNTD). We identified that polymer to be polyethylene terephthalate (PET) and found that it has a higher detection threshold compared to many other widely used SSNTDs which makes this detector particularly suitable for rare event search in cosmic rays as it eliminates the dominant low Z background. Systematic studies were carried out to determine its charge response which is essential before any new material can be used as an SSNTD. In this paper we describe the charge response of PET to 129 Xe, 78 Kr and 49 Ti ions from the REX-ISOLDE facility at CERN, present the calibration curve for PET and characterize it as a nuclear track detector.

Study of radiation background at various high altitude locations in preparation for rare event search in cosmic rays

Various phenomenological models presented over the years have hinted at the possible presence of strangelets, which are nuggets of Strange Quark Matter (SQM), in cosmic rays. One way to search for such rare events is through the deployment of large area Nuclear Track Detector (NTD) arrays at high mountain altitudes. Before the deployment of any such array can begin, a detailed study of the radiation background is essential. Also a proper understanding of the response of detectors exposed to extreme weather conditions is necessary. With that aim, pilot studies were carried out at various high altitude locations in India such as Darjeeling (2200 m a.m.s.l), Ooty (2200 m a.m.s.l) and Hanle (4500 m a.m.s.l). Small arrays of CR-39 as well as high threshold Polyethylene Terephthalate (PET) detectors were given open air exposures for periods ranging from three months to two years. The findings of such studies are reported in this paper.

A comparative study of alternative methods to determine the response of poly-ethylene terephthalate nuclear track detector

Abstract Two widely used methods of determining the etch-rate ratio in poly-ethylene terephthalate (PET) nuclear track detector are compared. Their application in different regimes of ion’s energy loss is investigated. A new calibration curve for PET is also presented.

PET: A High Threshold Nuclear Track Detector (NTD) for Rare Event Search

Search for rare events like strangelets or monopoles in cosmic rays or in particle accelerators is an active field of research. Nuclear Track Detectors (NTDs) are often the detectors of choice in such searches owing to their natural thresholds of registration which can suppress large parts or even the entirety of the background. A low-cost commercially available polymer in wide use as a packaging and bottling material, identified as Polyethylene Terephthalate (PET), was found to very effective as a NTD with detection threshold much higher than many other NTDs in wide use like CR-39, Lexan. Systematic studies were carried out to characterize and calibrate PET using ion beams from accelerators. In addition, pilot studies were carried out at various high-altitude locations where PET films were given open-air exposures. In this article, some of the results of those studies will be presented.