Construction of a portable vacuum chamber for the calibration of charged particle detectors

• Grant number: 16/25073-9
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: March 01, 2017
• End date: February 28, 2018
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geophysics
• Principal Investigator: Sandro Guedes de Oliveira
• Grantee: Isabela Castro de Moraes
• Host Institution: Instituto de Física Gleb Wataghin (IFGW). Universidade Estadual de Campinas (UNICAMP). Campinas , SP, Brazil

Abstract

In order to construct a portable vacuum chamber for calibration of fission fragment and alpha particle detectors, the student will build the experimental setup containing a PADC (Poly Allyl Diglycol Carbonate) particle detector and a source of alpha particles (thin films of Am-241, Ra-226 or natural uranium) inside a chamber. Considering the loss of energy of the particle when interacting in the air, it is necessary to use an apparatus with which it is possible to minimize this energy loss. For this, we can decrease the pressure inside the chamber using a sorption pump. The portable vacuum chamber will be formed by a capsule attached to a sorption pump. The sorption pump will be mounted with an adsorbent material that will cause the system pressure to drop. Inside the chamber, we will have a source fixed above a detector, which may have its inclination varied. After assembly of the system, detectors will be exposed to the charged particles sources. The angle of incidence on the detector will be varied. When interacting with the detector, the particle tracks, after a chemical etching process, can be observed under an optical microscope. We can use the maximum angle at which it is still possible to detect tracks, called the critical angle, for the determination of particle detection efficiency of the source system and detector. The assembled apparatus will have a reduced size and will be a stand-alone device by the use of the sorption pump. We expect to obtain a device that can be used inside a reactor to determine the efficiency in systems where the particles come from nuclear reactions, such as U-235 (n, fission), important for Fission Track Thermochronology, and B-10(n,alpha)Li-7, important in Boron Neutron Capture Therapy. (AU)