Olle Jonsson

SCANDAL - a facility for elastic neutron scattering studies in the 50-130 MeV range

A facility for detection of scattered neutrons in the energy interval 50 130 MeV, SCAttered Nucleon Detection AssembLy (SCANDAL), has recently been installed at the 20-180 MeV neutron beam facility of The Svedberg Laboratory, Uppsala. It is primarily intended for studies of elastic neutron scattering, but can be used for (n,p) and (n,d) reaction experiments as well. The performance of the spectrometer is illustrated in measurements of the (n,p) and (n,n) reactions on H-1 and C-12. In addition, the neutron beam facility is described in some detail

A facility for measurements of nuclear cross sections for fast neutron cancer therapy

A facility for measurements of neutron-induced double-differential light-ion production cross-sections, for application within, e.g., fast neutron cancer therapy, is described. The central detectio ...

Light‐Ion Production in the Interaction of 96 MeV Neutrons with Silicon

Double-differential cross sections for light-ion (p, d, t, He and α) production in oxygen, induced by 96 MeV neutrons are reported. Energy spectra are measured at eight laboratory angles from 20◦ to 160◦ in steps of 20◦. Procedures for data taking and data reduction are presented. Deduced energydifferential and production cross sections are reported. Experimental cross ∗Corresponding author, Tel. +46 18 471 6850, Fax. +46 18 471 3853, E-mail: stephan.pomp@tsl.uu.se

The Be-9(n,p)Li-9 reaction and the Gamow-Teller unit cross section

Double differential cross sections of the Be-9(n,p)Li-9 reaction have been measured at 96 MeV in the angular range 0 degrees-27 degrees up to about 20 MeV excitation energy. In addition, the C-12(n,p)B-12 reaction has been measured in the same angular and

The Pb-208(n,p)Tl-208 reaction at E-n=97 MeV

Abstract Double-differential cross sections of the 208 Pb(n,p) reaction have been measured at 97 MeV in the angular range 0°–30° for excitation energies up to 40 MeV. The experimental proton spectra have been compared with calculated spectra obtained with a statistical multistep direct reaction theory, in which charge exchange and inelastic response functions are described microscopically in the quasiparticle random phase approximation. The direct parts of the spectra have also been distributed on different multipole components by using a decomposition technique, based on sample angular distributions calculated within the distorted-wave Born approximation.

The response of a liquid scintillator detector to 21-100 MeV neutrons

A large volume ð 4l Þ liquid NE213 scintillator detector for neutrons in the energy range up to 800 MeV has been calibrated using a high accuracy tagging technique at En ¼ 21; 34; 50; 60 and 100 MeV. The experiment is described together with a discussion of the accuracy in the absolute efficiency calibration. Results are presented on total and differential detection efficiencies along with information on the underlying nuclear reactions causing the detector response, including both charged particles and g-rays. The present results complement previous measurements for the same detector, so that an efficiency calibration now exists over an energy range of En ¼ 2–800 MeV. The empirical results are compared with a calculated energy dependence of the detector response to neutrons. r 2002 Elsevier Science

Experimental Double-Differential Light-Ion Production Cross Sections for Silicon at 95 MeV Neutrons

The importance of cosmic radiation effects in aircraft electronics has recently been highlighted. At commercial flight altitudes, as well as at sea level, the most important particle radiation is due to neutrons, created in the atmosphere by spallation of nitrogen and oxygen nuclei, induced by cosmic-ray protons. When, e.g., an electronic memory circuit is exposed to neutron radiation, charged particles can be produced in a nuclear reaction. The charge released by ionization can cause a flip of the memory content in a bit, which is called a single-event upset (SEU). A similar logic error in one of the storage registers of a microprocessor may trigger an unanticipated loop that cannot be escaped without turning the unit off. To get a deeper understanding of these phenomena, more detailed cross section information on neutron-induced charged-particle production at intermediate energies is needed. To this end, double-differential cross sections of inclusive light-ion production in silicon, induced by 95 MeV neutrons, have been measured. The experiment was performed using the MEDLEY setup, which consists of eight three-element particle telescopes, covering the angular range 20° – 160°. The charged particles were identified using ΔE – ΔE – E techniques. By using an active target, consisting of a 300 μm thick Si detector, the energy loss in the target itself could be measured and corrected for.

Cross Section Data and Kerma Coefficients at 95 MeV Neutrons for Medical Applications

Motivated by the need of data on neutron-induced reactions with biologically relevant materials, e.g., carbon and oxygen, we have constructed and installed the MEDLEY detector array at the neutron beam facility of the The Svedberg Laboratory in Uppsala. The central detection elements of MEDLEY are three-detector telescopes, consisting of two silicon detectors and a Csl crystal. To cover wide energy and angle ranges, we have mounted eight such telescopes at 20° intervals. We have used ΔE − ΔE − E techniques to obtain good particle identification for protons, deuterons, tritons, 3He and α particles over an energy range from a few MeV up to 100 MeV. To define the detector solid angle, plastic scintillators were employed to serve as active collimators. We have up to now measured double-differential cross sections of inclusive light-ion production induced by 95 MeV neutrons on carbon and oxygen. From these data production cross sections, as well as partial kerma coefficients, are being determined. We have found that especially the proton kerma coefficient for carbon is substantially larger than that of a recent evaluation, leading to a larger total kerma coefficient. The obtained data supports a trend observed for similar data at lower energies.

SCANDAL - A Facility for Elastic Neutron Scattering Studies in the 50–130 MeV Range

Recently, a large number of applications involving high-energy (> 20 MeV) neutrons have become important. Examples are development of spallation sources, transmutation of nuclear waste, fast-neutron cancer therapy, as well as dose effects for airflight personnel and electronics failures due to cosmic-ray neutrons. Elastic neutron scattering plays a key role for the understanding of all these areas. The most important reason is that it allows a determination of the optical potential, which plays a decisive role in every microscopic calculation including neutrons in either the entrance or exit channel. In addition, the elastic cross section is also the largest of the individual partial cross sections contributing to the total cross section. A facility for detection of scattered neutrons in the energy interval 50–130 MeV, SCANDAL (SCAttered Nucleon Detection AssembLy), has recently been installed at the 20–180 MeV neutron beam facility of the The Svedberg Laboratory, Uppsala. It is primarily intended for studies of elastic neutron scattering, but can be used for the (n,p) t and (n,d) reaction experiments as well. The performance of the spectrometer is illustrated in measurements of the (n,p) and (n,n) reactions on 1H and 12 C at 96 MeV.

Neutron-Proton Scattering at Intermediate Energies - Recent, New and Future Measurements

A programme to investigate the neutron-proton scattering differential cross section at intermediate energies is active at the The Svedberg Laboratory, Uppsala, Sweden. Up to now, measurements of back angle differential np scattering cross sections have been undertaken at 96 MeV and 162 MeV. These high-precision data are well described by partial-wave analyses of other data sets over a wide angular range, but deviate at the most backward angles. However, they agree well in shape over the full angular range with another recent high-quality measurement from PSI. These results have large consequences for measurements of nuclear data for applications, because back angle np scattering is used as a primary standard. A new setup, SCANDAL (SCAttered Nucleon detection AssembLy), has been developed and installed for measurements aiming at clarifying the situation at back angles, as well as for forward-angle experiments, resulting in a complete angular distribution.