Elastic and inelastic photon scattering from 12C

doi:10.1016/0370-2693(94)91401-X

Physics Letters B

Volume 335, Issue 2, 1 September 1994, Pages 119-122

https://doi.org/10.1016/0370-2693(94)91401-X Get rights and content

Abstract

The elastic and inelastic photon scattering from ¹²C was investigated in the energy range of the Δ-resonance (E_γ = 200–500 MeV) at a scattering angle of 40°. The experiment was performed with the tagged photon facility at the cw electron accelerator MAMI (E_e− = 855 MeV). By using a large NaI(Tl) detector having an energy resolution of 1.5%, the elastic scattering could be separated from the inelastic process to the first excited state (E_x = 4.44 MeV of ¹²C. The differential cross section for the coherent scattering is compared with a simple static ansatz, that uses the known charge form factor, and with a recent Δ-hole calculation.

References (16)

J.H. Koch et al.
Ann. Phys.
(1984)
E. Hayward et al.
Nucl. Phys. A
(1984)
H. Arenhövel et al.
Phys. Lett. B
(1985)
J. Vesper et al.
Nucl. Phys. A
(1987)
I. Anthony et al.
Nucl. Inst. Meth. A
(1991)
W. Weise
Phys. Rep.
(1974)
J. Ahrens et al.
Nucl. Phys. A
(1988)
B. Dreher et al.
Nucl. Phys. A
(1974)

There are more references available in the full text version of this article.

Cited by (20)

Energy levels of light nuclei A = 12
2017, Nuclear Physics A
The upgraded photon tagging facility at the MAX IV Laboratory
2013, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
Citation Excerpt :
Fig. 12 is a single-hit TDC spectrum from an experiment in 2007 where the start signal (X-trigger) is from a nuclear detector and the stop signal is the software sum of the individual tagger channels. In this particular case the X-trigger came from a NaI(Tl) spectrometer used to study Compton scattering [29]. A correction has been applied to place the individual tagger channels into the same position; the correction accounts for delay due to different cable length or electronic delay, etc.
A description is given of the upgraded photon tagging facility at the MAX IV Laboratory. Two magnetic spectrometers are used to momentum analyze post-bremsstrahlung electrons. The tagged photon range extends from 10 to 180 MeV with an energy resolution of about 300 keV. The system has been operated at rates up to 4×10⁶ photons s^-1 MeV ⁻¹. Different diagnostic tools are described as well as the experimental program.
The response of lead-tungstate scintillators (PWO) to photons with energies in the range 13 MeV-64 MeV
2012, Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
The response of a matrix of 25 lead tungstate (PWO) scintillator detectors, operated at −25 °C, to photons in the range 13 MeV–64 MeV has been measured at the tagged-photon facility at MAX-lab, Lund. The tapered PWO crystals, each with a length of 200 mm and a cross-section of 24.4×24.4 mm² in the front end, read out by 19 mm photomultiplier tubes, were arranged in a 5×5 matrix. The response was measured for photons directed towards the centre of the central crystal as well as for photons directed towards the corner of the central crystal, where four crystals meet. The obtained energy resolution surpasses what has been published so far and is close to the limit given by Poisson statistics and escaped energy. For photons directed towards the centre(corner) of the central crystal the relative energy resolution, defined as (FWHM/2.35) $/ E_{γ}$ , decreases from 7.3%(11.0%) at $E_{γ} = 13 MeV$ to 3.3%(3.6%) at $E_{γ} = 64 MeV$ . The reconstructed point of impact of a photon in this energy range is determined with an uncertainty (one standard deviation) of 7.3±0.1 mm.
Compton scattering from the free and bound proton above π-threshold
2000, Nuclear Physics A
Compton scattering by nuclei
2000, Physics Report
The concept of Compton scattering by even–even nuclei from giant-resonance to nucleon-resonance energies and the status of experimental and theoretical researches in this field are outlined. The description of Compton scattering by nuclei starts from different complementary approaches, namely from second-order S-matrix and from dispersion theories. Making use of these, it is possible to incorporate into the predicted nuclear scattering amplitudes all the information available from other channels, viz. photon–nucleon and photon–meson channels, and to efficiently make use of models of the nucleon, the nucleus and the nucleon–nucleon interaction. The total photoabsorption cross section constrains the nuclear scattering amplitude in the forward direction. The specific information obtained from Compton scattering therefore stems from the angular dependence of the nuclear scattering amplitude, providing detailed insight into the dynamics of the nuclear and nucleon degrees of freedom and into the interplay between them. Nuclear Compton scattering in the giant-resonance energy-region provides information on the dynamical properties of the in-medium mass of the nucleon. Most prominently, the electromagnetic polarizabilities of the nucleon in the nuclear medium can be extracted from nuclear Compton scattering data obtained in the quasi-deuteron energy-region. In our description of this latter process special emphasis is laid upon the exploration of many-body and two-body effects entering into the nuclear dynamics. Recent results are presented for two-body effects due to the mesonic seagull amplitude and due to the excitation of nucleon internal degrees of freedom accompanied by meson exchanges. Due to these studies the in-medium electromagnetic polarizabilities are by now well understood, whereas the understanding of nuclear Compton scattering in the Δ-resonance range is only at the beginning. Furthermore, phenomenological methods how to include retardation effects in the scattering amplitude are discussed and compared with model predictions.
Compton scattering from the free and bound proton at backward angles above π-threshold
1999, Nuclear Physics A
Differential cross sections for Compton scattering from the free proton at Θ_γ′^lab=130.7° in the energy region from 200 MeV to 410 MeV and for quasi-free Compton scattering from the proton bound in the deuteron at Θ_γ′^lab=148.8° in the energy region from 200 MeV to 290 MeV have been measured. The free proton data are in agreement with dispersion-theory predictions based on standard parameters. The difference of the proton polarizabilities has been extracted from the quasi-free data. Our result, $α ̄ − β ̄ =[9.1±1.7(stat+syst)±1.2(mod)]×10^{−4} fm^{3}$ , is in reasonable agreement with the world average of the free proton data if the backward spin polarizability γ_π is taken to be $−37.6×10^{−4} fm^{4}$ as predicted by dispersion theory in agreement with many theoretical calculations. This implies that quasi-free Compton scattering may also be used to determine the electromagnetic polarizabilities of the neutron. No indication has been found of a recently suggested new contribution to γ_π.

View all citing articles on Scopus

^☆: Supported by Deutsche Forschungsgemeinschaft (SFB 201, Mainz and Az 438-113-71) and by Russian Fundamental Science Foundation (RFIF 02-14442).

View full text

Elastic and inelastic photon scattering from 12C☆

Abstract

Ann. Phys.

Nucl. Phys. A

Phys. Lett. B

Nucl. Phys. A

Nucl. Inst. Meth. A

Phys. Rep.

Nucl. Phys. A

Nucl. Phys. A

Elastic and inelastic photon scattering from ¹²C☆