Effect of the troposphere on surface neutron counter measurements
نویسنده
چکیده
Surface neutron counter data are often used as a proxy for atmospheric ionisation from cosmic rays in studies of extraterrestrial effects on climate. Neutron counter instrumentation was developed in the 1950s and relationships between neutron counts, ionisation and meteorological conditions were investigated thoroughly using the techniques available at the time; the analysis can now be extended using modern data. Whilst surface neutron counts are shown to be a good proxy for ionisation rate, the usual meteorological correction applied to surface neutron measurements, using surface atmospheric pressure, does not completely compensate for tropospheric effects on neutron data. Residual correlations remain between neutron counts, atmospheric pressure and geopotential height, obtained from meteorological reanalysis data. These correlations may be caused by variations in the height and temperature of the atmospheric layer at ~100hPa. This is where the primary cosmic rays interact with atmospheric air, producing a cascade of secondary ionising particles.
منابع مشابه
محاسبه ثابت کالیبراسیون شمارنده فعالسازی با پوشش نقرهای و مقایسه آن با نتایج تجربی بهمنظور اندازهگیری بهره نوترونی در دستگاه پلاسمای کانونی
The silver activation counters are commonly used for pulsed-neutron yield measurements especially in plasma focus devices. The counter normally consists of a Geiger-Muller tube along with silver foils and polyethylene (as a moderator), which is calibrated against an Am-Be radioisotope neutron source. The neutrons, after being slowed-down in the polyethylene, activate the silver foils. By measur...
متن کاملBehavior correction of the inverse square law in irradiation room for volumetric source and detector
The inverse-square law is used to calculate the radiation flux at difference distances from the source. This law is applied for point source and point detector in vacuum. This research aims to study the point behavior of volumetric source and detector by undertaking required corrections on inverse-square law through the elimination of scattered neutrons contribution. The measurements have been ...
متن کاملThe influence of neutron contamination on pacemaker in photon beam radiotherapy by LINAC using the Monte Carlo method
Introduction: In radiation therapy with high-energy photon beams (E > 7 MeV) neutrons are generated mainly in LINACs head thorough (γ, n) interactions. These neutrons affect the shielding requirements in radiation therapy rooms. According to the protocol TG-34, photon absorbed dose of 10Gy can cause permanent damage to the pacemaker and the dose of 2Gy can make minor changes in...
متن کاملNeutron Contamination Unexpected Dose in Varian LINAC
Introduction: Neutron contamination is very harmful for the patients receiving radiation therapy due to the high relative biological effect of neutrons. Medical linear accelerators head are made up of materials with high atomic numbers, and High-energy photons interaction with heavy materials can produce neutron contamination. In this study, neutron equivalent dose, neutron spe...
متن کاملThe influence of neutron contamination on pacemaker in photon beam radiotherapy by LINAC using the Monte Carlo method
In radiation therapy with high-energy photon beams (E > 10 MV) neutrons are generated mainly in LINACs head thorough (γ,n) interactions. These neutrons affect the shielding requirements in radiation therapy rooms. According to the AAPMTG-34 report, photon absorbed dose of 10Gy can cause permanent damage to the pacemaker and the dose of 2Gy can make minor changes in the functioning of the pac...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2005