Alberto Fasso

A comparison of FLUKA simulations with measurements of fluence and dose in calorimeter structures

Abstract Measurements have been recently published of the spatial variation of hadron and low-energy neutron fluence and of absorbed dose in the cascades induce

Wire scanners in low energy accelerators

Abstract Fast wire scanners are today considered as part of standard instrumentation in high energy synchrotrons. The extension of their use to synchrotrons working at lower energies, where Coulomb scattering can be important and the transverse beam size is large, introduces new complications considering beam heating of the wire, composition of the secondary particle shower and geometrical consideration in the detection set-up. A major problem in treating these effects is that the creation of secondaries in a thin carbon wire by a energetic primary beam is difficult to describe in an analytical way. We here present new results from a full Monte Carlo simulation of this process yielding information on heat deposited in the wire, particle type and energy spectrum of secondaries and angular dependence as a function of primary beam energy. The results are used to derive limits for the use of wire scanners in low energy accelerators.

Radiation levels in LEP, 1989–1995

Abstract This paper discusses the radiation levels monitored in and around the LEP tunnel and the underground experimental areas and in the environment on the surface, following the first six years of operation where the collider has mostly been working at 45 GeV (LEP phase I). At the end of 1995 the LEP II program was started, with an energy increase to 68 GeV. The radiation levels in the underground areas accessible during LEP operation are very low and on the surface the values of dose equivalent are not discernable from the background.

Comparison of measurements of angular hadron energy spectra, induced activity and dose with FLUKA82 calculations

Abstract Three experiments are described in which extended targets were bombarded with high-energy protons. The experiments were simulated using the Monte Carlo hadron cascade package FLUKA82. The measured and simulated quantities included the hadron yield around a target as a function of polar angle and energy and the two-dimensional ( r − z ) distributions of stars and energy deposition inside an aluminium cylinder. The agreement between the calculations and measurements is generally within experimental errors.

The yield of resonance neutrons from a thick copper target bombarded by electrons with energies up to 100 GeV

Abstract The yield of low-energy neutrons at 90° from a copper target bombarded by high-energy electrons varies from 0.015 GeV −1 ·sr −1 at 20 GeV to 0.035 GeV −1 ·sr −1 at 100 GeV. This yield is higher than would be expected from calculations based on the yield of giant resonance photo-neutrons alone. It is also shown that simple estimates of the yield from high-energy photon spallation interactions are unable to account for the measured values or their apparent dependence on energy. The measured yields are not incompatible with the approximate value of 0.33 GeV −1 recommended for use in shielding assessment at high-energy electron accelerators.