Experimental results of neutron fluence outside an iron shield in the forward direction
- Argonne National Lab., IL (United States)
- Fermi National Accelerator Lab., Batavia, IL (United States)
- Arizona Univ., Tucson, AZ (United States)
- Ball State Univ., Muncie, IN (United States)
- Minnesota Univ., Minneapolis, MN (United States)
- Northern Illinois Univ., De Kalb, IL (United States)
Analyses of both lateral shielding measurements and Monte Carlo calculations for beam stop geometry for incident hadrons at energies between 10 GeV and 10 TeV suggests that the dose equivalent can be represented by the expression H = H{sub 0}(E)e{sup -r/{lambda}}/r{sup 2} where H, is the source term, r is the radial distance to the point of interest in the shield, and {lambda} is the effective interaction length, or absorption mean free path. However, unlike the lateral shielding case, there is no similarly simple analytical expression that can be used to describe the on-axis longitudinal cascade development. In this study the results from the measurement in the forward direction of neutron fluence spectra (and the derived quantity dose equivalent) for 25 to 150 GeV pions incident on an iron beam stop as a function of thickness of iron are presented. The observed dependence of both fluence and dose equivalent on shield thickness and hadron energy was then quantified in terms of an expression in which a build up factor as well as an attenuation term was included. On the basis of this analysis the conversion factor from fluence to dose equivalent was also determined for these forward going neutrons. This work represents the first systematic study at an high energy accelerator of the depth dependence of neutron fluence in longitudinal shielding.
- Research Organization:
- Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
- Sponsoring Organization:
- USDOE Office of Energy Research, Washington, DC (United States)
- DOE Contract Number:
- AC02-76CH03000; W-31109-ENG-38
- OSTI ID:
- 419223
- Report Number(s):
- FNAL/C-96/333; ANL/ESH/CP-91289; CONF-970134-6; ON: DE97050000; TRN: 97:001766
- Resource Relation:
- Conference: 30. midyear topical meeting of the Health Physics Society, San Jose, CA (United States), 5-8 Jan 1997; Other Information: PBD: Sep 1996
- Country of Publication:
- United States
- Language:
- English
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