Polymer-based detectors to search for cosmic particles
doi:10.1038/nindia.2016.17 Published online 5 February 2016
By using a commercially available polymer, physicists have developed a nuclear track detector that produces tiny pit-like tracks when exposed to ion beams1. Measuring the shape and size of the tracks helps decipher the charge, energy and direction of motion of the incident ions.
An array of such nuclear track detectors could potentially be used to detect hypothetical particles such as strangelets in cosmic rays. Strangelets are conjectured to consist of subatomic particles such as up, down and strange quarks.
The researchers produced the nuclear track detector using the polymer polyethylene terephthalate. They probed this detector’s potential to detect strangelets in cosmic radiation by separately exposing it to proton and carbon beams of different energies inside a target chamber.
Exposure to proton beams possessing an energy of 2 mega electron volts for 4 and 9 hours failed to create any tracks on the detector’s polymer film. In contrast, exposure to 11-mega-electron-volt carbon beams produced micrometer-sized tracks.
A 1-hour exposure to a carbon beam formed visible tracks smaller than a micrometer, whereas a 4-hour exposure generated tracks larger than 5 micrometres.
The polymer is a promising material for detecting the presence of low-energy, heavily ionizing particles such as strangelets in cosmic radiation, the researchers say.
1. Bhattacharyya, R. et al. Determination of the detection threshold for polyethylene terephthalate (PET) nuclear track detector (NTD). Nucl. Instrum. & Meth. Phys. Res. B 370, 63–66 (2016)