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The Maastro Proton Therapy Centre is the first European facility housing the Mevion S250i Hyperscan synchrocyclotron. The proximity of the accelerator to the patient, the presence of an active pencil beam delivery system downstream of a passive energy degrader and the pulsed structure of the beam make the Mevion stray neutron field unique amongst proton therapy facilities. This paper reviews the results of a rem-counter intercomparison experiment promoted by the European Radiation Dosimetry Group at Maastro and compares them with those at other proton therapy facilities. The Maastro neutron H*(10) in the room (100–200 μSv/Gy at about 2 m from the isocentre) is in line with accelerators using purely passive or wobbling beam delivery modalities, even though Maastro shows a dose gradient peaked near the accelerator. Unlike synchrotron- and cyclotron-based facilities, the pulsed beam at Maastro requires the employment of rem-counters specifically designed to withstand pulsed neutron fields.

Objective. Proton therapy is gaining popularity because of the improved dose delivery over conventional radiation therapy. The secondary dose to healthy tissues is dominated by secondary neutrons. Commercial rem-counters are valuable instruments for the on-line assessment of neutron ambient dose equivalent (H*(10)). In general, however, a priori knowledge of the type of facility and of the radiation field is required for the proper choice of any survey meter. The novel Mevion S250i Hyperscan synchrocyclotron mounts the accelerator directly on the gantry. It provides a scanned 227 MeV proton beam, delivered in pulses with a pulse width of 10 μs at 750 Hz frequency, which is afterwards degraded in energy by a range shifter modulator system. This environment is particularly challenging for commercial rem-counters; therefore, we tested the reliability of some of the most widespread rem-counters to understand their limits in the Mevion S250i stray neutron field. Approach. This work, promoted by the European Radiation Dosimetry Group (EURADOS), describes a rem-counter intercomparison at the Maastro Proton Therapy centre in the Netherlands, which houses the novel Mevion S250i Hyperscan system. Several rem-counters were employed in the intercomparison (LUPIN, LINUS, WENDI-II, LB6411, NM2B-458, NM2B-495Pb), which included simulation of a patient treatment protocol employing a water tank phantom. The outcomes of the experiment were compared with models and data from the literature. Main results. We found that only the LUPIN allowed for a correct assessment of H*(10) within a 20% uncertainty. All other rem-counters underestimated the reference H*(10) by factors from 2 to more than 10, depending on the detector model and on the neutron dose per pulse. In pulsed fields, the neutron dose per pulse is a fundamental parameter, while the average neutron dose rate is a secondary quantity. An average 150–200 μSv/GyRBE neutron H*(10) at various positions around the phantom and at distances between 186 cm and 300 cm from it was measured per unit therapeutic dose delivered to the target. Significance. Our results are partially in line with results obtained at similar Mevion facilities employing passive energy modulation. Comparisons with facilities employing active energy modulation confirmed that the neutron H*(10) can increase up to more than a factor of 10 when passive energy modulation is employed. The challenging environment of the Mevion stray neutron field requires the use of specific rem-counters sensitive to high-energy neutrons (up to a few hundred MeV) and specifically designed to withstand pulsed neutron fields.

During high altitude long haul flights pilots, cabin crew and passengers are exposed to enhanced level of radiation originating from cosmic ray showers (CRS), produced via the interaction of very high-energy (~GeV) primary protons with the air molecules in Earth's atmosphere. The CRS are composed of energetic particles of diverse species, i.e. neutrons, protons, electrons, muons, pions and photons. Furthermore, the magnitude of aircrew radiation exposure depends on flight altitude and duration, geographical location (latitude), geomagnetic conditions and solar activity (modulation) status. In 1990 the International Commission on Radiological Protection (ICRP) classified airline crewmembers as “radiation workers”. A miniature passive microdosimeter (LiBe-14) based on LiF (TLD700) and Beryllium Oxide (BeO) thermoluminescence dosimeter chips emulating a large volume gas-filled Tissue Equivalent Proportional Counter (TEPC) was developed by one of the authors (BM). The LiBe-14 was deployed to assess the integrated ambient dose equivalent of two commercial pilots on long haul intercontinental flights during March–May 2017. The accumulated dose equivalents of 1st (38 y, Female, 148 total block hours) and 2nd (29 y, Male, 149 total block hours) pilots were evaluated to be 565 μSv ± 105 μSv and 738 μSv ± 137 μSv, respectively. The results agreed well within ±20% of simulated data evaluated using the well-known EPCARD ( E uropean P rogram Package for the C alculation of A viation R oute D oses) aviation dosimetry code. The implementation of LiBe-14 Microdosimeter in routine long haul, high-altitude commercial flights for the estimation of dose equivalent, average LET and quality factor relevant to impinging cosmic radiation is recommended.

Monitoring soil moisture is still a challenge: it varies strongly in space and time and at various scales while well established sensors typically suffer from a small spatial support. With a sensor footprint up to several hectares, Cosmic-Ray Neutron Sensing (CRNS) is an emerging technology to address that challenge. So far, the CRNS method has typically been applied with single sensors or in sparse national scale networks. This study presents, for the first time, a dense network of 24 CRNS stations that covered, from May to July 2019, an area of just 1 km2: the pre-alpine Rott headwater catchment in Southern Germany which is characterized by strong soil moisture gradients in a heterogeneous landscape with forests and grasslands. With substantially overlapping sensor footprints, that network was designed to study root zone soil moisture dynamics at the catchment-scale. The observations of the dense CRNS network were complemented by extensive measurements that allow to study soil moisture variability at various spatial scales: roving (mobile) CRNS units, remotely sensed thermal images from Unmanned Areal Systems (UAS), permanent and temporary wireless sensor networks, profile probes as well as comprehensive manual soil sampling. Since neutron counts are also affected by hydrogen pools other than soil moisture, vegetation biomass was monitored in forest and grassland patches, as well as meteorological variables; discharge and groundwater tables were recorded to support hydrological modeling experiments. As a result, we provide a unique and comprehensive dataset to several research communities: to those who investigate the retrieval of soil moisture from cosmic-ray neutron sensing, to those who study the variability of soil moisture at different spatio-temporal scales, and to those who intend to better understand the role of root-zone soil moisture dynamics in the context of catchment and groundwater hydrology, as well as land – atmosphere exchange processes. The data set is available through EUDAT, splitted into the two subsets https://doi.org/10.23728/b2share.85fe0f9dac0f48df9215c17e65d1f1e1 (Fersch et al., 2020a) and https://doi.org/10.23728/b2share.93ed99e486904d48a8a6a68083066198 (Fersch et al., 2020b).

National Institute of Advanced Industrial Science and Technology, 1-1-1 Umezono, Tsukuba, Ibaraki, 305-8568 Japan; Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo, 152-8350 Japan; High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki, 305-0801 Japan; Japan Atomic Energy Agency, 2-4 Shirakata, Tokai-mura, Naka-gun, Ibaraki-ken, 319-1195, Japan; e Kyoto University, 2-1010 Asayo-nishi, Kumatori-cho, Sennan-gun, Osaka, 590-0494 Japan; f German Reserach Center for Enviromental Health, 85764 Neuherberg, Germany; g Research Center for Nuclear Physics, Osaka University, 10-1 Mihogaoka, Ibaraki, Osaka, 567-0047 Japan; h Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai, Miyagi, 980-8578 Japan

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 9V 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 30km and then soft-landed aided by a self-deploying parachute 66.2km 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±0.05μSv. Furthermore, a high-altitude extended version of commercially available aviation dosimetry package EPCARD.Net (European Program package for the Calculation of Aviation Route Doses) 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±0.09μSv. The important aspects of balloon based near-space radiation dosimetry are highlighted in this paper.

This note discusses the significant impact on effective doses received during commercial flights calculated using the new International Commission on Radiological Protection (ICRP) radiation weighting factors. It also provides an update on adult effective doses given in a previous article in Health Physics when the old ICRP radiation weighting factors were used.

The neutron responses of Bonner sphere spectrometric systems with a 4 mm × 4 mm6LiI scintillator and with a 3He (32 mm diameter) proportional counter were calculated using the MCNP Monte Carlo code for the energy range 14.8 to 100 MeV. Calculated responses have been interpolated to evaluate the response matrix for both systems; data tables are available on diskette.

The neutron response matrix for a Bonner sphere spectrometric system with a 3.2 cm diameter 3He proportional counter is calculated applying the MCN

Pionic X-rays from A1, Fe and Cu have been measured with an intrinsic germanium detctor using a counter telescope. The measured transition energies and intensities have been compared with the computer calculated values.