High resolution characterisation of laser accelerated protons for radiation hardness studies

Mihai Ganciu
DFT Seminar Room
2019-07-04 12:00:00


A new method for the proton energetic distribution determination is presented (OSIM Patent Application, A/00337/05-06-19) The method can be applied to diagnose protons such as: those generated owing to the interaction between a plasma and a high power laser beam, protons present in cosmic radiation, protons for medical applications, etc. Accurate determination of the proton energetic spectrum, and particularly the maximum energy acquired after the laser-pulse solid target interaction, enables one to estimate the electron temperature. This issue is very important for developing applications of interest for Radiation Hardness Assurance, by simulating the aggressive radiation environment form the outer space by means of laser-plasma accelerators. The method proposed to determine the energetic spectrum of protons is based on using a set of solid detectors, preferably CR-39. Each detector is thinner than the Bragg peak that characterizes the loss of kinetic energy on the unit length, as a function of the particle track in the detector material. The Bragg peak is characterized by an intense peak whose position is a clear indication of the particle location where the particle loses the largest part of its kinetic energy. For protons the Bragg peak occurs right before stopping. The thickness of the Bragg peak region is defined as the full width at half maximum (FWHM) of the energy loss curve, that describes the specific energy deposition dE/dx of a heavy charged particle as a function of the penetration depth. The Bragg peak width, that corresponds to proton energy in the 3 ÷ 15 MeV range, is about 0.2 mm. Under such case, the thickness of the CR-39 detector should not exceed 0.2 mm. The method we devised circumvents some of the disadvantages associated with previous methods, and brings in the following advantages:
- It enhances the resolution used to determine the proton energy and extends the interval of energy values for which the method is applicable. This characteristics is useful for proton beams with energy spread over a wide range of values
- The etching process is simultaneously performed for all solid detectors. Consequently, etching is performed faster, under identical conditions for all solid CR-39 detectors.

https://arxiv.org/abs/1906.00779, 14 Jun 2019

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