Residual radiation studies at AP0
The radiation environment at the NuMI experiment has received a lot of attention in the last few years in preparation for project construction. One important issue is the induced radioactivation of the components in the beam line and the shielding materials. This arises from irradiation by hadrons that are generated in the target. Since the level of the residual activity has to be considered when determining access procedures for maintenance during NuMI operation, an understanding of the properties of the remnant radiation is important. To this end, experimental studies were performed in the target vault at AP0 which is similar in design to the NuMI target area. Here 120 GeV protons bombard a target, generating the hadrons that produce the induced radioactivity. Two sets of samples each consisting of three small cylindrical or rectangular solids of iron and steel, one sample of aluminum, and one of concrete were irradiated. One set was hung just below the bottom of a module near the lithium lens (in-vault), and the other was placed on top of the modules downstream of this location (above-vault), just beneath the movable concrete roof of the vault at AP0. Further, four thin activation foils of Au, Au+Cd, In, and Al (along with small disks of the same iron, aluminum, and concrete samples discussed above) were mounted on four 10.2 cm diameter Al disks, one placed on the in-vault module and three at above-vault downstream locations as well. The radioactivity of all these materials on the 10.2 cm Al disks was determined at the Radioisotope Analysis Facility in an attempt to characterize the radionuclides produced during irradiation. The activities of the thin foils were employed in an effort to unfold a spectrum of the neutrons produced during the hadronic cascades in the target. The MARS Monte Carlo code (MO95, MO00) was used to predict and analyze the residual radiation produced during the beam irradiation. New subroutines have been developed for the MARS14 version providing reliable estimation of residual dose rates in arbitrary composite materials for arbitrary irradiation and cooling times (RA01). The results of the simulations have been compared with the measurements in Ref. (RA01) and this comparison will be summarized here.
- Research Organization:
- Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
- Sponsoring Organization:
- USDOE Office of Energy Research (ER) (US)
- DOE Contract Number:
- AC02-76CH03000
- OSTI ID:
- 795488
- Report Number(s):
- FERMILAB-TM-2176; TRN: US0201334
- Resource Relation:
- Other Information: PBD: 19 Jun 2002
- Country of Publication:
- United States
- Language:
- English
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