Linear Energy Transfer Spectrometry Research Articles

Measurement of neutron dose from p+181Ta reaction at different proton energies via LET spectrometry

While measuring the neutron dose in accelerator radiation environment using CR-39 detector for radiation protection purpose, LET (linear energy transfer) spectrometry method is implemented when the information about the radiation source term is unknown. In this work, the neutron dose has been measured for p+181Ta reaction at different proton energies i.e. 8–20 MeV by LET spectrometry method using CR-39 detectors. The track density in CR-39 was found to increase exponentially with the proton energy and an empirical relation has been established. The dosimetric quantities viz. absorbed dose (DLET) and dose equivalent (HLET) were determined from the LET spectra and both these quantities were found to be increasing with the proton energy. Empirical relations were generated, which will be useful for predicting dose in similar radiation environment. The dosimetric data generated in this study would be useful for radiation protection of occupational workers working in the accelerator radiation environment.

Generation and application of LET calibration curve for neutron dosimetry using CR-39 detector and microwave induced chemical etching.

Microwave induced chemical etching (MICE) has been established as a faster and improved technique compared to other contemporary etching techniques for the development of tracks in a CR-39 detector. However, the methodology could not be applied for LET (linear energy transfer) spectrometry due to lack of a calibration curve using this method. For this purpose, a new LET calibration curve in the range of 12 keV/μm-799 keV/μm was generated considering different ions such as H, Li, C, O, and F on CR-39 having different LETs in water. An empirical relation was established from the obtained calibration curve for determining the value of LET (in water) from the value of V, the ratio of track etch rate to bulk etch rate. For application of this calibration curve in neutron dosimetry, CR-39 detectors were irradiated to neutrons generated from 120 and 142 MeV 16O+27Al systems followed by a similar MICE procedure. The absorbed dose (DLET) and the dose equivalent (HLET) were obtained from the LET spectra and were found to be 13% and 10% higher for 142 MeV 16O+27Al system than those for 120 MeV 16O+27Al system, respectively. The outcome of the study demonstrates the possibility of using the MICE technique for neutron dose estimation by CR-39 via LET spectrometry.

Comparison of neutron doses measured by CR-39 via LET spectrometry and neutron rem meter

Neutron dose for proton induced reactions on the combination of 7Li and 181Ta target was measured using CR-39 detector and a neutron rem meter, at five different proton energies (8–24 MeV). In case of CR-39, the dose equivalent (HLET) was measured via linear energy transfer (LET) spectrometry method using the major, minor radii of each track and thickness of removed surface, whereas the rem meter provided the direct reading of ambient dose equivalent [H*(10)]. Both these quantities per incident proton were found to increase with the proton energy. The response ratio of HLET to [H*(10)] was found to be in the range of 0.15–0.3 with an average 0.20 ± 0.09.

Neutron dose estimation via LET spectrometry using CR-39 detector for the reaction (9)Be (p, n).

CR-39 detectors, widely used for neutron dosimetry in accelerator radiation environment, have also been applied in tissue microdosimetry by generating the linear energy transfer (LET) spectrum. In this work, the neutron dose has been estimated via LET spectrometry for 9Be (p, n) reaction which is useful for personnel monitoring around particle accelerators and accelerator based therapy facilities. Neutrons were generated by the interaction of protons of 6 different energies from 4–24 MeV with a thick Be target. The LET spectra were obtained from the major and minor radii of each track and the thickness of removed surface. From the LET spectra, the absorbed dose (DLET) and the dose equivalent (HLET) were estimated using Q-L relationship as given by International Commission on Radiological Protection (ICRP) 60. The track density in CR-39 detector and hence the neutron yield was found to be increasing with the increase in projectile (proton) energy. Similar observations were also obtained for absorbed dose (DLET) and dose equivalents (HLET).

Spectrometry of linear energy transfer with track-etched detectors in carbon ion beams, MONO and SOBP

Five various materials employed as track-etched detectors (TEDs) were exposed in beams of carbon ions with energy 290 MeV. u(-1) in the HIMAC-BIO facility in Japan. The exposures were performed behind various types of polymethyl methacrylate shielding. The beam had two possible set-ups--monoenergetic set-up and modulated spread-out Bragg peak set-up. All used TEDs are polyallyl diglycol carbonates (PADCs): Page from Mouldings (Pershore) Ltd, Tastrak from Track Analysis Systems Ltd, both from the UK; USF4 from American Technical Plastics from the USA and two products of Japan Fukuvi Chemical Industry Co., Ltd--TD1 and Baryotrak. Spectra of linear energy transfer and depth-dose distributions were obtained. Besides, differences among PADCs are discussed.

Spectrometry of linear energy transfer and dosimetry measurements onboard spacecrafts and aircrafts

There are only a few methods of dosimetry which can estimate the contribution of different particles to onboard spacecraft and/or aircraft exposure. This contribution describes an attempt to estimate the contribution of different components to the exposure level using MDU-Liulin energy deposition spectrometer and thermoluminescent detectors (TLD’s), in combination with a spectrometer of linear energy transfer (LET) based on track etch detectors. This equipment was exposed onboard: the International Space Station for a long period and two shorter shuttle missions and a commercial subsonic aircraft for several long-term monitoring periods from 2001 to 2006. The data obtained are analyzed from several points of view and the obtained results are presented, analyzed, and discussed.

Spectrometry of linear energy transfer and its use in high-energy particle beams

A new method to determine the spectra of linear energy transfer (LET) based on track-etch detectors has been developed. It is based on chemically etched polyallyldiglycolcarbonate (PADC) track detector. LET spectra are calculated using the track parameters measured with an automatic optical image analyzer. This method has been recently improved; the calibration curves have been upgraded on the basis of evaluating the detectors exposed in heavier high-energy charged particle beams. The LET spectrometer has been used to determine LET spectra and integral dosimetry characteristics along the range of protons, resp. 12C ions with primary energies of 205 MeV, resp. about 480 MeV/amu; and to study the importance of the fragmentation and nuclear reactions in carbon and other heavier ion beams. The results obtained are analyzed and discussed; the possible advantages of this type of equipment are outlined.

To the spectrometry of linear energy transfer in charged particle beams by means of track-etch detectors

The contribution describes the methodology of linear energy transfer (LET) spectrometry based on the chemically etched track detectors and results of some experimental studies. Three types of polyallyldiglycolcarbonate (PADC) material have been used in our laboratory: Page—with a thickness of 0.5 mm and Tastrak with thicknesses of 0.5 and 1 mm. This LET spectrometer is able to detect charged particles with LET above the registration threshold (around 10 keV / μ m , depending on the used material), both primary and secondary, created through nuclear interactions in the detector itself or in the surroundings. During several years the detectors were irradiated by various particles with LET in water up to about 600 keV / μ m . In these studies, primary heavy ions had LET above the registration threshold and so they can be directly detected. However, also some fragments and products of nuclear reactions of the primary particles are registered in the detector, especially behind various absorbers. LET spectrometer calibration curves and also the importance of secondary particles in heavy ion beams and their contribution to the absorbed dose are presented and discussed.

LET spectrometry with track etch detectors—Use in high-energy radiation fields

For assessing the risk from ionizing radiation it is necessary to know not only the absorbed dose but also the quality of the radiation; radiation quality is connected with the physical quantity linear energy transfer (LET). One of the methods of determination of LET is based on chemically etched track detectors. This contribution concerns with a spectrometer of LET based on the track detectors and discusses some results obtained at: • high-energy radiation reference field created at the SPS accelerator at CERN; and • onboard of International Space Station where track-etch based LET spectrometer has been exposed 273 days during “Matrjoshka – R” experiment. Results obtained are compared with the results of studies at some lower-energy neutron sources; some conclusions on the registrability of neutrons and the ability of this spectrometer to determine dose equivalent in high-energy radiation fields are formulated.

Spectrometry of linear energy transfer with track etched detectors

Spectrometry of linear energy transfer with track etched detectors

Spectrometry of linear energy transfer with a track etched detector

Etchable track formation in a track etch detector is a process directly related to the density of energy deposition by a charged particle in the detector. The analysis of track parameters would therefore permit to determine the linear energy transfer (LET) of a particle and its spectra in exposed track detectors. The contribution describes the method of LET Spectrometry based on the track parameter analysis in chemically etched polyallyldiglycolcarbonate. It is founded on the etch rates ratios determination using an automatic image analyzer, the calibration had been performed by heavy charged particles. The range of etch rate ratios established corresponded to the LET in tissue between 100 and 6000 MeV.cm 2.g −1. The method was tested in the field of a 252Cf neutron source, the LET spectra established in some other beams and fields are also presented.