Abstract
This paper discusses an experimental study of the spallation reaction 27Al(p,3pn)24Na in Al foils exposed to 24GeVc−1 protons, in the context of monitoring the intensity of multi-GeV proton beams through foil activation techniques. Since this reaction is sensitive to secondary neutrons and other energetic secondary hadrons, it is important to evaluate the impact of the foil thickness on the calculation of the beam intensity. This effect is determined experimentally using a stack of Al foils of varying thickness. The experimental results are then compared to Monte Carlo simulations.
Highlights
Different methods can be employed to measure the intensity of high-energy proton beams [1,2]
Among the devices used for this task are: Faraday cups [1,3] measuring the electrical charge of the beam, beam current transformers (BCTs) [4,5] measuring the magnetic field induced by the charged beam, as well as scintillators [6,7], ionisation chambers [8,9] and secondary electron emission chambers (SECs) [10,11] that measure the energy deposited by the beam in matter
The single- and multi-foils aluminium activation techniques were investigated and compared at the CERN IRRAD facility to measure the total number of protons impinging on the foils
Summary
Different methods can be employed to measure the intensity of high-energy proton beams [1,2]. Each technique has some limitations: Faraday cups are destructive and show peak power issues; BCT work only at high beam currents and are generally employed for pulsed beams; scintillators are not radiation hard and present saturation effects above a certain threshold; ionisation chambers generate very low outputs; SECs are usually employed for intensities of at least few hundred pA. The total number of protons impinging on the samples is measured by the activation (determined by γ-spectrometry measurements) of the aluminium foil [13]. This technique is used to calibrate active instrumentation [14]
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