Charles D. Goodman

Energy Systematics of the Giant Gamow-Teller Resonance and a Charge-Exchange Dipole Spin-Flip Resonance

Energy systematics of the giant Gamow-Teller resonance and a charge-exchange resonance excited by a L = 1, S = 1 interaction are presented. Plots of the energy separation between each resonance and the IAS versus (N − Z)A can be represented approximately by linear functions.

Search for isobaric analogues of M1 states and giant spinflip resonances in the 208Pb(p, n) reaction

Abstract The 208 Pb(p, n) 208 Bi reaction has been studied at E p =120 and 160 MeV . The GT resonance is found to be concentrated in disagreement with a recent theoretical suggestion that it is highly fragmented in heavy nuclei, but in good agreement with an earlier calculation. A giant Δl = 1, ΔS = 1 resonance is also observed.

A Facility for Studying Neutron Energy Spectra at Intermediate Energies

Apparatus for measuring neutron energy spectra in the 50-200 MeV range is described. The apparatus, installed at the Indiana University Cyclotron Facility, consists of a beam swinger to change the angle of incidence of the beam on target, 100 m flight paths, large, subnanosecond neutron detectors, and a system for deriving phase stabilized timing signals.

Elastic and inelastic scattering of 88 MeV 6Li ions

Abstract The elastic scattering of 88 MeV 6 Li ions has been studied for eleven targets ranging in mass from 24 Mg to 208 Pb. Angular distributions were measured from about 10° c.m. in steps of 0.5°, mostly out to 60 or 70° c.m. where the elastic cross sections range from 10 −3 to 10 −5 of the Rutherford values. Inelastic data for exciting the lowest 2 + states of 24,26 Mg and 60 Ni were also obtained. The elastic data were analyzed using the optical model, with potentials of both Woods-Saxon and double-folding forms. The analysis confirms that the potentials for 6 Li obtained from the folding model with the M3Y interaction need renormalizing by about 0.6, in agreement with results obtained at other energies. The inelastic data were compared to distorted-wave calculations. Coupled-channels analyses were also made for 24, 26 Mg, 60 Ni and 59 Co. Reorientation effects were found to be important to give the correct 2 + angular distributions for 24, 26 Mg and could also account for the differences between the elastic scattering from the odd- A and adjacent even- A targets.

Comparison of the 12C(p, n)12N and 12C(p, p′) reactions at Ep = 62 and 120 MeV☆

Abstract Measured 12 C(p, p′) and 12 C(p, n) 12 N reaction cross-section angular distributions leading to isobaric analog states are compared at 62 and 120 MeV bombarding energies. It is shown that the (p, p′) differential cross section is one-half the (p, n) differential cross section to the analog state. This relation and these reactions are demonstrated to be very useful for the determination of the detection efficiency of large volume neutron detectors at intermediate energies.

High Efficiency Detectors for Time-of-Flight with High Energy Neutrons

We discuss our experience in achieving sub-nanosecond time resolution with neutrons about 100 MeV on a scintillation detector 15 × 15 × 100 cm viewed by a single phototube. Time compensation is accomplished by tilting the scintillator axis with respect to the neutron flight path as discussed in a previous paper. We also discuss the interplay between the time compensation from the geometry of light collection and the electronic technique for picking off the time signal.

States in 8Be studied through the reaction 11B(p, α)8Be with 40 MeV protons

Abstract Spectroscopy of the α- and τ-particles from 40 MeV proton bombardment of 11 B reveals transitions to 8 Be states up to 19 MeV. The ratio of excitation of the 16.6 MeV state to the 16.9 MeV state is 2.3 ± 0.4. The 8 Be(4 + ) state is found at 12.5 MeV with a width of 4.0 ± 0.5 MeV. States in 9 Be excited most strongly are the g.s. and 2.43 MeV level; a state at 3.1 MeV is excited with about 1 % of the strength of the g.s. transition. Angular distributions show forward-peaking for all states.

The Use of Arrays Smaller than Implied by the Range of Descriptors for Multiparameter Pulse Height Analysis

A program for use with multiparameter pulse height analysis is described. The main purpose of the program is to permit reasonably rapid accumulation of data into arrays which are much smaller than implied by the range of descriptors. In addition the method readily permits the use of descriptors which exceed the bit capacity of the computer word. Any grouping of zero and non-zero channels as is observed in most real spectra is especially exploited. In many cases, the data can be retained in a packed array in core memory until the actual number of non-zero channels becomes almost as large as the allotted core-memory space, at which time the array is transferred to another space in core (where it will be transferred onto disc as a background operation), the core array is reinitialized, and the data acquisition is continued. With this procedure, multichannel arrays as large as the available disc memory can be stored on disc without the data acquisition suffering from the very slow random access time of the disc. Methods of data handling and the resulting effective counting rates are discussed.

Data Acquisition Computer with Foreground-Background Operating System

An on-line data acquisition computer system is described which runs background computational programs while it is acquiring data independently of and asynchronously with the program. A combination of hardware and software prevents loss of data and destruction of the system through errors in Fortran background programs.

A System for Multiparameter Pulse Height Analysis with Repeated Use of a Single, Fast ADC

In many nuclear physics experiments an event consists of correlated output pulses from several radiation detectors. We call each separate output pulse a parameter. The experiments with which we are dealing are multiparameter experiments. We have constructed a system in which a single ADC is interfaced to a general purpose computer. Multiparameter experiments are handled by storing the several pulses in analog stretchers and using the ADC repeatedly to digitize the several pulses in sequence. This approach is made practical by the availability of a very fast ADC. The system includes features that give it unusual flexibility for handling complicated time relationships among the pulses. The use of one rather than several ADCs makes the system simpler, more compact, and less expensive than multiple ADC systems. Provisions are included for evaluating counting loss due to dead time of the system for random or non-random event distributions. The data transfer logic incorporates the facility for including digital information from devices in addition to the ADC in each event datum.