Calibration of the Large Solid Angle Detector

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Near-threshold measurement of the 4He(g,n) reaction

A near-threshold 4He(g,n) cross-section measurement has been performed at MAX-lab. Tagged photons from 23 < Eg < 42 MeV were directed toward a liquid 4He target, and neutrons were detected by time-of-flight in two liquid-scintillator arrays. Seven-point angular distributions were measured for eight photon energies. The results are compared to experimental data measured at comparable energies and Recoil-Corrected Continuum Shell Model, Resonating Group Method, and recent Hyperspherical-Harmonic Expansion calculations. The angle-integrated cross-section data is peaked at a photon energy of about 28 MeV, in disagreement with the value recommended by Calarco, Berman, and Donnelly in 1983.Comment: 10 pages, 3 figures, some revisions, submitted to Physics Letters

Measurements of 12C(&#8594;γ,pp) photon asymmetries for Eγ= 200–450 MeV

The 12C (&#8594;γ ,pp) reaction has been studied in the photon energy range 200-450 MeV at the Mainz microtron MAMI-C, where linearly polarised photons were energy-tagged using the Glasgow-Mainz Tagged Photon Spectrometer and protons were detected in the Crystal Ball detector. The photon asymmetry Σ has been measured over a wider Eγ range than previous measurements. The strongest asymmetries were found at low missing energies where direct emission of nucleon pairs is expected. Cuts on the difference in azimuthal angles of the two ejected protons increased the magnitude of the observed asymmetries. At low missing energies the Σ data exhibit a strong angular dependence, similar to deuteron photodisintegration

Neutron propagation in 12C for energies 20 to 45 MeV

Neutron transmission in 12C has been estimated by analyzing 12C(gamma,pn) and 12C(gamma,p) data, that were collected simultaneously using the Mainz Microtron (MAMI-A) tagged-photon system, at photon energies from 80 to 157 MeV. Correction has been made for solid angle and threshold effects by use of a Monte Carlo simulation. The corrected ratio of the (gamma,pn) and (gamma,p) data gives an indication of the proportion of emitted protons that have an accompanying neutron. This ratio, which can be interpreted as a lower limit for the neutron transmission in 12C, has been found to be O.80±O.08 for the 20-45 MeV neutrons examined in this experiment. Since the data sets were collected simultaneously, systematic uncertainties associated with the tagger and proton detector cancel in the ratio

Involving young people in research

Full report 'Involving young researchers' by P. Kirby, is published for the Foundation by YPS, ISBN 1-902163345-8SIGLEAvailable from British Library Document Supply Centre-DSC:3927.734141(Dec 1999, N89) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

PiP - A large solid angle scintillation telescope for detecting protons and pions

A ~1 sr solid angle scintillation detector hodoscope for protons of up to ~280 MeV and positive pions of up to ~180 MeV energy has been developed for use in (gamma,pN), (gamma,p pi±) and (gamma,pi+ N) experiments with tagged photons. This paper reports the detailed design of the hodoscope and its performance for detecting protons and positive pions

The reception of Lucan's De Bello Civili in the nineteenth century

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN027563 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Near threshold photoproduction of η-mesons from complex nuclei

Total and differential cross sections for photoproduction of eta mesons from 12C, 4OCa, 93Nb, and natPb have been obtained up to 790 MeV incident photon energy at the Mainz Microtron (MAMI) with the TAPS spectrometer. The absorption cross section sigma_etaN = (30 ± 2.5 ± 6)mb of eta mesons in nuclear matter and the absorption length lambda = (2.0 ± 0.2 ± 0.4) fm are extracted. No significant depletion of the Sll(1535) strength in the eta photoproduction on nuclei is observed