P. D. Zecher

A large-area, position-sensitive neutron detector with neutron/γ-ray discrimination capabilities

Abstract To further study neutron-rich halo nuclei, we have constructed a neutron detector array. The array consists of two separate banks of detectors, each of area 2 × 2m 2 and containing 250l of liquid scintillator. Each bank is position-sensitive to better than 10 cm. For neutron time-of-flight measurements, the time resolution of the detector has been demonstrated to be about 1 ns. By using the scintillator NE-213, we are able to distinguish between neutron and γ-ray signals above 1 MeV electron equivalent energy. Although the detector array was constructed for a particular experiment it has also been used in a number of other experiments.

Neutron cross-talk in a multi-detector system

Abstract Two 2 m × 2 m “walls” were built for experiments with two neutrons in the final state. Each wall consists of 25 rectangular cells filled with NE-213 liquid scintillator. The close-packed design of the array makes cross-talk an inevitable contributor to distortion of measurements with this system. For E n ≤ 25 MeV almost all the detection efficiency comes from n-p scattering, and the simple two-body kinematics can be used as the basis for identifying cross-talk events. A Monte-Carlo code was developed to simulate the detection process. We found that most cross-talk events could be distinguished from real two-neutron events. A test experiment for comparison with the code was performed with neutrons from the 7 Li(p, n) 7 Be reaction at E p = 30 MeV. With this reaction all two-detector coincidences are cross-talk events. Consistency between the experimental data and the simulation results was obtained.

Comparison of two liquid scintillators used for neutron detection

The pulse-shape discrimination capability and the scintillation e

Neutron/γ-ray pulse-shape discriminator

ciency of two liquid scintillators, BC519 and NE213 (BC501A) have been compared. Pulse-shape discrimination is not as good with BC519, but for large light pulses it should be adequate in many applications and may be a useful alternative to NE213 because it has a higher ratio of H-to-C atoms. Within 5% the scintillation e

Fragment detection system for studies of exotic neutron-rich nuclei

ciencies are the same when the scintillators are excited by protons with energies up to 11 MeV. ( 2000 Elsevier Science B.V. All rights reserved.

Optical transmission of Mylar and Teflon films

We present a neutron/γ-ray pulse-shape discriminator that is inexpensive and highly stable. Both of these favorable attributes come from the fact that the basic element of the device is a length of co-axial cable. The quality of discrimination is similar to that obtained with other modern devices.

Erratum to: “Comparison of two liquid scintillators used for neutron detection” [Nucl. Instr. and Meth. A 440 (2000) 241–244]

We have developed a fragment detection system for use in studies of exotic, neutron-rich nuclei. Using a C-shaped dipole magnet, the system sweeps charged fragments and un-reacted beam particles through an angle before stopping them in an array of plastic scintillator detectors, recording time-of-flight and total energy. The system also includes a pair of silicon strip detectors to measure fragment angle of emergence from the target and energy loss for particle identification.

Evidence for a proton halo in B 8 : Enhanced total reaction cross sections at 20 to 60 MeV/nucleon

In an application involving light transmission via total internal reflection, the light is attenuated at each reflection by passage through a thin film. To choose a film that would minimize the attenuation we had to measure the optical properties of Mylar and Teflon. Our results showed that type-D Mylar was preferable.

Total reaction and 2n-removal cross sections of 20-60A MeV 4,6,8He, 6-9,11Li, and 10Be on Si

akos@ludens.elte.hu (AD. HorvaHth).1Present address. National Instutute of Radiological Sciences, 9-1 Anagawa 4-Chome, Inage-ku, Chiba 263, Japan.2Present address. Radiation Oncology, Mayo Clinic, 200 First St. SW, Rochester, MN 55905, USA.3Present address. American Express Co., 3WFC, 4712B, 200 Vesey Street, New York, NY 10285, USA.4Present address. Physical Department, University of California, Berkeley, CA 94720, USA.5Present address. Investor Analytics LLC, 630 Fifth Avenue, Suite 1919, New York 10111, USA.Nuclear Instruments and Methods in Physics Research A 446 (2000) 601