T. S. Subramanian

Neutron induced charged particle spectra and kerma from 25 to 60 MeV

Abstract Neutron beams in the tens of MeV range are widely used in biomedical applications. At these energies the reaction channels open to charged particles increase compared to the situation prevailing below about 15 MeV. An extensive program to measure charged particle products on tissue-resident elements (H, O, C, and N) has been carried out at Crocker Nuclear Laboratory. The particles detected include protons, deuterons, tritons, helium-3 and alphas, measured over a wide angular range for neutron energies of 27.4, 39.7, and 60.7 MeV. Good agreement is found in comparison with charge symmetric proton-induced energy spectra (such as in (p,d) vs. (n,d)). Kerma have been obtained at the three energies for each nucleus including elastic recoil contributions. The use of sum rules to obtain the missing (non-elastic) contribution from heavier fragments is examined. These experimental kerma values are found to be considerably different than predictions by several authors. Recent calculations by Brenner and by...

Thick target corrections for charged particle spectra

Abstract A method is presented which allows charged particle spectra from thick targets to be corrected for energy and particle loss in the target. The method is applied to the (n, xα ) reaction in carbon and to alpha decay in uranium.

Measurements of 7Li(p,n) and 9Be(p,n) cross sections at 15, 20 and 30 MeV

Abstract Cross sections have been measured at 0° for the (p,n) reaction on 7Li and 9Be for 15, 20, and 30 MeV protons incident on thin targets. Results are presented as a function of neutron energy for neutrons above about 3 MeV.

Electron capture by protons in a neutron beam facility

Abstract Relative measurements of electron capture probabilities for protons of 42.5 and 61.8 MeV are presented. Attention is drawn to some uses of the resulting beam in a 0° neutron beam facility.

An experimental facility for measurement of charged particle continua arising from neutron induced reactions

Abstract A facility to measure neutron-induced charged-particle continua using beams of 25–60 MeV is described. The heart of the facility consists of the production and collimation of a neutron beam into a scattering chamber containing the target and three independent detector telescopes. Each telescope contains three elements and provides good particle identification for p, d, t, 3 He, and α. While “ E - δE ” displays are used to identify energetic particles, a time-of-flight versus pulse-height scheme is used to identify low-energy alphas (from 3–8 MeV) that stop in the first element. Good timing and energy resolution obtained with this system allow the simultaneous measurement of hydrogen and helium isotopes with a wide range of energies: from about 3–60 MeV. Corrections to measured spectra relevant to this set-up are discussed. This facility has been used to obtain extensive data on neutron-induced reactions on tissue-resident elements such as carbon, nitrogen and oxygen.