Feasibility of short-lived radionuclide production at Fermilab

The feasibility of establishing a facility for short-lived radionuclide production hinges on the availability of the Fermilab injector linac and on how such a program would fit in with the primary mission of the laboratory. The linac is available 168 hours per week except for scheduled maintenance, which typically does not exceed one to two shifts per week, and HEP requirements. The laboratory may be reluctant to make a commitment for the routine production of SLRs however, due to its understanding of the requirements for reliable scheduled delivery of targets. But, the laboratory is also quite interested in establishing industrial liaisons. It would be willing to explore feasible industrial proposals, especially with regards to developing a research-type facility where the technology and methods developed at Fermilab could be utilized elsewhere

Update of neutron dose yields as a function of energy for protons and deuterons incident on beryllium targets

Neutron absorbed dose yields (absorbed dose rates per unit incident current on targets at a given SAD or SSD) increase with incident charged particle energy for both protons and deuterons. Analyses of neutron dose yield versus incident particle energy have been performed for both deuterons and protons. It is the purpose of this report to update those analyses by pooling all of the more recent published results and to reanalyze the trend of yield, Y, versus incident energy, E, which in the past has been described by an expression of the form Y = aE/sup b/, where a and b are empirical constants. From the reanalyzed trend it is concluded that for a given size cyclotron (E/sub p/ = 2E/sub d/), the dose yields using protons are higher than those using deuterons up to a proton energy E/sub p/ of 64 MeV

New look at displacement factor and point of measurement corrections in ionization chamber dosimetry

A new technique is presented for determination of the effective point of measurement when cavity ionization chambers are used to measure the absorbed dose due to ionizing radiation in a dense medium. An algorithm is derived relating the effective point of measurement to the displacement correction factor. This algorithm relates variations of the displacement factor to the radiation field gradient. The technique is applied to derive the magnitudes of the corrections for several chambers in a p(66)Be(49) neutron therapy beam. 30 references, 4 figures, 1 table

Variable Curvature Phantom

The design of a variable curvature dosimetry phantom is briefly described. The phantom was developed to test the accuracy of the dose modification algorithms used to estimate dose distributions inside patient contours. 1 fig. (ACR

Scaling neutron absorbed dose distributions from one medium to another

Central axis depth dose (CADD) and off-axis absorbed dose ratio (OAR) measurements were made in water, muscle and whole skeletal bone TE-solutions, mineral oil and glycerin with a clinical neutron therapy beam. These measurements show that, for a given neutron beam quality and field size, there is a universal CADD distribution at infinity if the depth in the phantom is expressed in terms of appropriate scaling lengths. These are essentially the kerma-weighted neutron mean free paths in the media. The method used in ICRU No. 26 to scale the CADD by the ratio of the densities is shown to give incorrect results. the OAR's measured in different media at depths proportional to the respective mean free paths were also found to be independent of the media to a good approximation. It is recommended that relative CADD and OAR measurements be performed in water because of its universality and convenience. A table of calculated scaling lengths is given for various neutron energy spectra and for various tissues and materials of practical importance in neutron dosimetry

Anti W comparisons for A150 plastic-equivalent gases, TE gas, and air

As part of our continuing evaluation of A150 plastic equivalent gases for neutron dosimetry, we have measured ionization ratios which are related to anti W ratios between gases in the p(66)Be(49) neutron beam at Fermilab. Additionally we have extended our earlier measurements (DeLuca, et al., 1980) at the UW gas target /sup 3/H(d,n)/sup 4/He neutron source to include an uncollimated beam geometry with ion chambers close to the target. Observed differences from the earlier results can probably be explained on the basis of neutron spectra, which await further determination