Dosimetry of secondary cosmic radiation up to an altitude of 30 km

Abstract

Dosimetric measurements in the field of secondary cosmic radiation were extensively made during the last years. Since the majority of these measurements were performed on-board passenger aircraft at altitudes between 10 and 12 km, measurements at higher altitudes are desirable for the verification of the legal dose assessment procedures for aircrew. A simple solution is to use a high-altitude balloon that reaches altitudes as high as 30 km. In this work, it is shown that the dose rate profile up to 30 km can be measured with acceptable uncertainties using a Si-detector.

Cosmic radiation dose measurements from the RaD-X flight campaign

“…The dose equivalent rate increases with altitude until it reaches a plateau at the conventional Pfotzer maximum, as seen in the TEPC absorbed dose rate profile in Figure . The absence of a distinct Pfotzer maximum in dose equivalent rate was not observed in previous balloon flights where the onboard dosimeters were largely insensitive to high‐LET events [ Advisory Committee for Radiation Biology Aspects of the SST (ACRBASST) , ; Foelsche et al , ; Wissmann et al , ]. A plateau in the dose equivalent rate occurs at about 21 km in the profile computed using the sliding window average.…”

The disappearance of the pfotzer-regener maximum in dose equivalent measurements in the stratosphere

“… The altitude profile for absorbed dose (both in silicon and in tissue) illustrates the Pfotzer‐Regener maximum in atmospheric ionization rates at around 60,000 feet. The influence of indirectly ionizing particles (particularly primary cosmic ray protons) at higher altitudes effectively eliminates this peak in the altitude profile for dose equivalent. This is due to the high relative biological effectiveness (RBE) of dose from high LET secondaries from interactions with these particles, as reflected in quality factors applied during the calculation. This “disappearance” of the Pfotzer‐Regener maximum in the context of dose equivalent has not previously been observed from balloon flights that have carried simpler instruments with no calibrated response to indirectly ionizing particles [ Wissmann et al, ; http://Earthtosky.net/the‐research]. Therefore, for radiation protection considerations, it should not be assumed that biological dose rates decrease at very high altitudes in the stratosphere. The energy deposition spectrum from RaySure provides direct evidence of this high LET population of particles above the Pfotzer‐Regener maximum.…”

Overview of the Liulin type instruments for space radiation measurement and their scientific results

“…7) was successfully launched on a HotPay2 rocket from the Andoya Rocket Range (ARR), Norway, on 31 January 2008 at 19:14:00 UT as a part of an EU-financed scientific program called eARI (ALOMAR eARI project) and attained an altitude of 380 km. Wissmann et al (2013) performed five balloon experiments up to 30 km altitude using Liulin-6RG spectrometers (see Table 2, Item No. 8) between July 2011 and August 2012.…”

“…The TEPC data are plotted in Fig. 4 using the opportunity provided by Zapp (2013) and by the 'Coordinated Data Analysis Web' at the NASA-Goddard Space Flight Center (http :/ /cdaweb .gsfc .nasa .gov/).…”