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This paper reports the near space ballooning experiment carried out at Australian outback town West Wyalong (33°51′S, 147°24′E) on 19 July 2015. Several dedicated electronic detectors including digital temperature and acceleration (vibration) sensors and an energy compensated PIN-diode gamma ray dosimeter were installed in a thermally insulated Styrofoam payload box. A 9 V Lithium-Polymer battery powered all the devices. The payload box was attached to a helium-filled latex weather balloon and set afloat. The balloon reached a peak burst altitude of 30 km and then soft-landed aided by a self-deploying parachute 66.2 km away form the launch site. The payload box was retrieved and data collected from the electronic sensors analysed. The integrated cosmic ray induced photon ambient dose equivalent recorded by the PIN diode detector was evaluated to be 0.36 ± 0.05 μSv. Furthermore, a high-altitude extended version of commercially available aviation dosimetry package EPCARD.Net ( E uropean P rogram package for the C alculation of A viation R oute D oses) was used to calculate the ambient dose equivalents during the balloon flight. The radiation environment originated from the secondary cosmic ray shower is composed of neutrons, protons, electrons, muons, pions and photons. The photon ambient dose equivalent estimated by the EPCARD.Net code found to be 0.47 ± 0.09 μSv. The important aspects of balloon based near-space radiation dosimetry are highlighted in this paper. [ABSTRACT FROM AUTHOR]

The ratio of thermoluminescence light outputs (TLO) of Beryllium Oxide (BeO) and Lithium Fluoride (LiF) dosimeters increases with increasing LET (Linear Energy Transfer) of the impinging particles on the dosimeter chips. This unique phenomenon was utilized to develop a microdosimeter using the common LiF (TLD-700) and BeO (American Beryllia-CF5427-000) dosimeter chips. The dosimeter pairs were exposed to complex mixed radiation fields produced by bombarding a polystyrene plate phantom with therapeutic proton beams of energies from 81 to 231 MeV at the West German Proton Therapy Centre Essen (WPE), Germany. The linear energy transfer (LET) and quality factor ( Q ) of the secondary radiation fields were simultaneously estimated using a REM 500B tissue equivalent proportional counter (TEPC). The TLD chips were evaluated and the corresponding LET and Q values were plotted as linear functions of the ratio of the TL-glow curve areas within 100–250 °C of TLD-700 and BeO chips. The TLD pairs embody a passive, solid-state, tissue-equivalent, microdosimeter that enable the delivery of dose equivalent (DE), dose-average LET and Q within a broad dynamic range for a given mixed-radiation field relevant to particle therapy, long haul aviation dose monitoring and human space exploration. [ABSTRACT FROM AUTHOR]

Abstract: On 27 April 2006 a vacuum ultra violet free electron laser (FEL) named free electron laser in Hamburg (FLASH) producing intense beams of 13.1nm laser light became operational. A 260m long, 1GeV superconducting electron linear accelerator (linac) drives the FLASH. The electron linac is made of an array of superconducting niobium cavities developed at DESY on TESLA technology. During the FEL operation a parasitic radiation field of photoneutrons and bremsstrahlung gamma rays persists in the linac containment tunnel. Sophisticated measurement and control devices, based on radiation-sensitive commercial off the shelf (COTS) microelectronic components, have been installed near the FLASH linac. Therefore, it becomes necessary to characterise these stray radiations, in order to predict the radiation effects on electronics. This paper summarises the features of novel radiation dosimeters and accelerator dosimetry techniques developed by our group. The utilisation of valuable radiation dosimetry data gathered from the experiments at FLASH to predict the radiation field characteristics of the future European X-ray free electron laser (XFEL) driven by a 20GeV superconducting electron linac is highlighted. [Copyright &y& Elsevier]

Abstract: During the beam adjustment of high energy accelerator facilities, a significant number of energetic particles impinge on the internal wall of the vacuum chamber thereby causing the production of intense parasitic radiation field, resulting in a short-term radiation exposure to personnel as well as interference in the operation of accelerator instrumentation systems usually based on sophisticated microelectronics. High-energy particle accelerators operate in pulsed mode; therefore, commercially available, general purpose radiation detectors for health physics activities are unsuitable for the assessment of such radiation field due to “pulse pile-up” effects. Hence, we have used passive neutron dosimeters, i.e. temperature compensated superheated emulsion (bubble) detectors of types BDPND and BDT, to evaluate the neutron fluence at three selected locations of the 7.6GeV proton synchrotron operated by DESY: (a) the 1.2-m thick concrete shielding roof of the experiment hall housing the proton synchrotron, (b) the 0.9-m thick shielding roof of the proton injector hut, and (c) at the lateral wall (2.5m concrete and earth shielding) of the experiment hall, facing the proton injector delivering 7.6GeV protons into the PETRA booster ring. [Copyright &y& Elsevier]

Abstract: The bremsstrahlung energy spectrum generated by the 450MeV electron linac driving the vacuum ultra violet free electron laser FLASH (free electron laser in Hamburg) operated by DESY was measured with TLD-700 detectors and unfolded using a technique based on a genetic algorithm. The half (1/2), one-fourth (1/4) and tenth (1/10) value layer thickness of lead were estimated to be 1.0, 4.0 and 20mm, respectively. The peak and average photon energy were calculated from the unfolded bremsstrahlung spectrum and found to be 0.5 and 0.8MeV, respectively. [Copyright &y& Elsevier]

Abstract: The SrS:Ce,Sm phosphor is suitable for operation in harsh radiation environments where real-time dosimetry measurements are needed to survey the Total Ionizing Dose (TID) damage in electronic components. For these applications, the OSL and RL emissions from this phosphor can be exploited by mounting the SrS crystal at the edge of a single, radiation-hard, optical fiber. In this work we present an exhaustive characterization of this real-time OSL/RL probe including stability, repeatability of the measured signals, dosimetry performance and measurements of the temporal behavior of the RL signal in pulsed particle beams. [Copyright &y& Elsevier]