The CERN-EU High-energy Reference Field (CERF) Facility for Dosimetry at Commercial Flight Altitudes and in Space

Radiation protection around CERN's high-energy accelerators represents a major challenge due to the presence of complex, mixed radiation fields. Behind thick shielding neutrons dominate and their energy ranges from fractions of eV to about 1 GeV. In this work the response of various portable detectors sensitive to neutrons was studied at CERN's High-Energy Reference Field Facility (CERF). The measurements were carried out with conventional rem counters, which usually cover neutron energies up to 20 MeV, the Thermo WENDI-2, which is specified to measure neutrons up to several GeV, and a tissue-equivalent proportional counter. The experimentally determined neutron dose equivalent results were compared with Monte Carlo (MC) simulations. Based on these studies field calibration factors can be determined, which result in a more reliable estimate of H Ã (10) in an unknown, but presumably similar high-energy field around an accelerator than a calibration factor determined in a radiation field of a reference neutron source.

Section: Introductionmentioning

confidence: 99%

Response of neutron detectors to high-energy mixed radiation fields

Mayer¹,

Forkel-Wirth²,

Fuerstner³

et al. 2006

“…The measurements were performed behind a 80-cm thick concrete shield in the CT7 reference exposure location (1) . At this location the neutron spectral fluence is characterised by a low-energy peak with an energy around 0.4 eV, an intermediate region between the thermal and the evaporation peak located at 1 MeV and a high-energy peak centred at 100 MeV (1) .…”

Section: Instrumentationmentioning

confidence: 99%

“…At this location the neutron spectral fluence is characterised by a low-energy peak with an energy around 0.4 eV, an intermediate region between the thermal and the evaporation peak located at 1 MeV and a high-energy peak centred at 100 MeV (1) . Both commercial and prototype detectors were employed, which can be divided in three classes:…”

Section: Instrumentationmentioning

confidence: 99%

“…Measurements in such complex radiation environments can lead to huge variations in detector readings, due to differences in their energy response function and sensitivity. With the aim of evaluating the performance of various active monitors in a well-characterised mixed field, an intercomparison campaign was carried out in 2012 at the CERN-EU reference field (CERF) facility (1) .…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Instrument intercomparison in the high-energy mixed field at the CERN-EU reference field (CERF) facility

Caresana¹,

Helmecke²,

Kubančák³

et al. 2013

Self Cite

This paper discusses an intercomparison campaign performed in the mixed radiation field at the CERN-EU (CERF) reference field facility. Various instruments were employed: conventional and extended-range rem counters including a novel instrument called LUPIN, a bubble detector using an active counting system (ABC 1260) and two tissue-equivalent proportional counters (TEPCs). The results show that the extended range instruments agree well within their uncertainties and within 1s with the H*(10) FLUKA value. The conventional rem counters are in good agreement within their uncertainties and underestimate H*(10) as measured by the extended range instruments and as predicted by FLUKA. The TEPCs slightly overestimate the FLUKA value but they are anyhow consistent with it when taking the comparatively large total uncertainties into account, and indicate that the non-neutron part of the stray field accounts for ∼30 % of the total H*(10).

“…Details about the facility and the reference positions can be found in ref. (4) . During the measurements a set of hydrogen-filled IG5 ionisation chambers was placed at different exposure locations (see Table 1) outside of the concrete shielding and measurements were conducted for beam intensities of 500, 1000, 2000 and 4000 PIC counts.…”

Section: Studies At the Cerf Facilitymentioning

confidence: 99%

Field calibration studies for ionisation chambers in mixed high-energy radiation fields

Theis

Forkel-Wirth

Fuerstner

et al. 2007

The monitoring of ambient doses at work places around high-energy accelerators is a challenging task due the complexity of the mixed stray radiation fields encountered. At CERN, mainly Centronics IG5 high-pressure ionisation chambers are used to monitor radiation exposure in mixed fields. The monitors are calibrated in the operational quantity ambient dose equivalent H*(10) using standard, source-generated photon-and neutron fields. However, the relationship between ionisation chamber reading and ambient dose equivalent in a mixed high-energy radiation field can only be assessed if the spectral response to every component and the field composition is known. Therefore, comprehensive studies were performed at the CERN-EU high-energy reference field facility where the spectral fluence for each particle type has been assessed with Monte Carlo simulations. Moreover, studies have been performed in an accessible controlled radiation area in the vicinity of a beam loss point of CERN's proton synchrotron. The comparison of measurements and calculations has shown reasonable agreement for most exposure conditions. The results indicate that conventionally calibrated ionisation chambers can give satisfactory response in terms of ambient dose equivalent in stray radiation fields at high-energy accelerators in many cases. These studies are one step towards establishing a method of 'field calibration' of radiation protection instruments in which Monte Carlo simulations will be used to establish a correct correlation between the response of specific detectors to a given high-energy radiation field.