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Measurements are reported for the light output response on a NaI(T1) detector for protons, deuterons, and tritons with energies between 30 and 60 MeV. The stopping power region covered by this data overlaps previous data taken with electrons and protons. The new data around 60 MeV is interesting in that the light output is greater for deuterons (and tritons) than that for protons by the equivalent of ≈ 1 MeV. A comparison is made with the model of Murray and Meyer for light output response in inorganic crystals.

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.

A large solid angle, high counting rate detection system for p, d t identification and energy measurement in the range of 15 to 65 MeV has been developed. The detector consists of two position-sensitive delay-line multiwire chambers, a thin plastic scintillator ΔE, and two large area NaI E detectors. Measurements of energy spectra of protons from 12C(n, p) are presented.

A new type of detector for measuring neutron flux and energy over a wide range of angles and energies is being developed. Measurements of neutron elastic and inelastic scattering as well as neutron energy continua are possible. Time-of-flight is not used for measuring outgoing neutron energy, and so for continuum measurements this system has some distinct advantages over conventional neutron detectors. Neutron energy measurement is carried out by measuring the energy and angle of the recoil proton produced by the neutron in a CH2 converter. Spectra from 7Li(p, n)7Be at 62 MeV and 40Ca(n, n′χ) at 65 MeV are presented.

The parent analog of the giant dipole resonance in 28 Si is studied by means of the (n, p) reaction. The continuum contribution to the giant dipole region was estimated by a phenomenological parameterization. The observed cross section exhausts 31% of the SJ sum rule; 88% of the GT sum rule or 67% of the Myers-Swiatecki prediction. A comparison is made to the giant resonance region observed in the 28 Si(p, p') reaction which was recently used, via comparison to 28 Si(α, α'), to infer that the GDR in 28 Si is not excited or at least not seen in (p, p').

A method is described for making small (2–6 μl) localized intracerebral drug injections in the conscious monkey. A base plate and guide cannula are initially secured to the skull under general anaesthesia. A mechanical pump containing the drug solution and fitted with an injection needle is located on the base plate assembly. In the conscious animal the pump is triggered magnetically to deliver a predetermined volume into the target brain region.

A method for measuring neutron non-elastic cross sections at medium energies is described. The method uses a relatively thick target and a large solid angle neutron detector which intercepts most of the elastically scattered neutrons. The non-elastic cross section is determined from attenuation measurements and a knowledge of the total cross section, the relative elastic cross section (as given by optical model predictions) and the relative efficiency of the detector. Measurements for C, O, Ca and Fe at 40 and 50 MeV have been carried out using this method.

Neutron total non-elastic cross sections have been obtained from transmission measurements of 40.3 and 50.4 MeV neutrons on C, O, Ca, and Fe. The results agree within error bars with proton data on the same nuclei. The data are well represented by the relation sigma/sub non/=..pi..(r/sub 0/A/sup 1/3/+lambda-dash-bar)/sup 2/, where r/sub 0/1.21=(plus-or-minus0.03) fm. Comparisons of sigma/sub non/ with optical model calculations for C and O show a preference for the parameters of Bassel and Herling, while for Ca both the parameter sets of Patterson and those of Becchetti and Greenlees work reasonably well. None of the parameter sets is entirely satisfactory for Fe. Implications of these data for the isospin dependence of the optical model are discussed.

Double differential cross sections for the neutron-induced production of p, d, t, $^{3}\mathrm{He}$, and alpha particles from carbon have been measured using unpolarized neutrons. Neutron beam energies of 27.4, 39.7, and 60.7 MeV were used. The charged particle energy spectra at nine laboratory angles---15, 20, 35, 40, 45, 65, 90, 130, and 150 deg---range up to the kinematic maximum, from a lower energy cutoff of 4 MeV for p, d, t, and alpha and 8 MeV for $^{3}\mathrm{He}$. A CH target was used so that the absolute normalization was obtained simultaneously from the n-p cross sections. Intranuclear cascade plus deexcitation calculations were carried out. The data are compared with these calculations and with available proton induced (charge symmetric) reaction spectra.NUCLEAR REACTIONS $^{12}\mathrm{C}(\mathrm{n}, \mathrm{p}x; \mathrm{d}x; ^{3}\mathrm{H}x; ^{3}\mathrm{He}x; ^{4}\mathrm{He}x)$, ${E}_{\mathrm{n}}=27.4, 39.7, 60.7$ MeV; measured $\ensuremath{\sigma}(\ensuremath{\theta}; E)$, ${\ensuremath{\theta}}_{\mathrm{lab}}=15, 20, 35, 40, 45, 65, 90, 130, 150$ deg. Intranuclear cascade plus deexcitation calculations.

Data were accumulated for the (n, p) reaction on 14N and 16O using 60MeV neutrons. Angular distributions of the cross sections for eight proton groups were extracted and compared to distorted-waves Born approximation (DWBA) calculations using a simple macroscopic model. Enhancements in the spectra were seen in each case in the region of excitation corresponding to the giant dipole resonance (GDR) of the target nucleus. DWBA calculations show that these excitations are primarily dipole and favor the use of the Goldhaber-Teller form factor. Comparison with photo-absorption measurements suggests that there may also be significant contributions to the (n, p) reaction from “spin-flip” dipole excitations. The other proton groups could be correlated with the results of other experiments and include excitations of analogs of the giant isovector “magnetic” dipole mode of 14N.

A new type of neutron flux and energy-measuring detector, which uses large-area ΔE and E detectors, and multiwire chambers (MWC) is being developed. The purpose is to allow one to measure neutron elastic and inelastic scattering and in particular to measure (n,xn) neutron continuum over a wide energy range. The detector offers many distinct advantages over the conventional neutron time-of-flight (TOF) method. The system was tested using a large area CH2 converter to produce recoil protons, which are tracked in the two MWC’s and registered in the AE and E detectors. A 7Li(p,n) spectrum from 62 MeV protons was measured and a 40Ca(n,n′) spectrum from 65 MeV neutrons was also measured.

Double-differential cross sections for the neutron-induced production of p, d, t, $^{3}\mathrm{He}$, and alpha particles from oxygen and nitrogen have been measured using an unpolarized neutron facility. Neutron beam energies of 27.4, 39.7, and 60.7 MeV were used. The charged particle energy spectra, at six forward laboratory angles, 15, 20, 35, 40, 45, and 65, and, where feasible, at three backward angles, 90, 130, and 150 deg, range up to the kinematic maximum, from a typical low-energy cutoff of 4 MeV for p, d, t, and alpha particles, and 8 MeV for $^{3}\mathrm{He}$. Intranuclear cascade plus deexcitation calculations were carried out. The data are compared with these calculations and with available proton-induced (charge-symmetric) reaction spectra for oxygen.