Photoproduction of mesons and Compton scattering on the proton: Selected results from the A2 Collaboration at MAMI

The A2 Collaboration performs a manifold research program using real photons in the Crystal Ball/TAPS experiment at the MAMI accelerator facility in Mainz. The experiments take advantage of high- intensity unpolarized, linearly or circularly polarized photon beams, and unpolarized or polarized targets. The detector setup provides almost complete coverage in solid angle and is well suited for the detection of multi particle final states. In order to probe the internal structure of the nucleon, the spectrum of baryon resonances is studied via measurements of unpolarized cross sections and various polarization observables in single and double meson photoproduction. The program aiming to determine the scalar and spin polarizabilities of the nucleons with high precision is performed with the Compton scattering experiments. In 2017, the focal plane detector used in the tagging system of the Crystal Ball/TAPS experiment was completely renewed, allowing new measurements with unprecedentedly high precision. This paper presents recent selected results from the A2 Collaboration at MAMI.

Download Full-text

States in 152Sm populated by the (t,α) reaction

Canadian Journal of Physics ◽

10.1139/p77-152 ◽

1977 ◽

Vol 55 (13) ◽

pp. 1137-1144 ◽

Cited By ~ 22

Author(s):

C. R. Hirning ◽

D. G. Burke

Keyword(s):

Cross Sections ◽

Attenuation Factor ◽

Matrix Elements ◽

Coriolis Coupling ◽

Reaction Products ◽

Plane Detector ◽

Scientific Laboratory ◽

Coupling Calculation ◽

Good Agreement ◽

Focal Plane Detector

Levels in the deformed even–even nucleus 152Sm have been populated by the (t,α) reaction using beams of 15 MeV tritons from the model FN tandem Van de Graaff accelerator at the Los Alamos Scientific Laboratory. For the initial experiments in the series the reaction products were analyzed in an Elbek magnetic spectrograph and detected with nuclear emulsions. Those done later made use of the Q3D magnetic spectrometer and helical-cathode focal plane detector. On the basis of levels observed in adjacent odd-Z nuclei and some previous (α,2nγ) results, a rotational band built on the Kπ = 5−, 5/2+[413] + 5/2−[532] two-quasiparticle state has been identified. A Coriolis coupling calculation has been done, which gives good agreement with experimental energies and cross sections when an attenuation factor of 0.31 is used for the Coriolis matrix elements.

Download Full-text

HIGHLIGHTS OF CRYSTAL BALL PHYSICS

International Journal of Modern Physics A ◽

10.1142/s0217751x05023013 ◽

2005 ◽

Vol 20 (08n09) ◽

pp. 1575-1581 ◽

Cited By ~ 1

Author(s):

◽

B. M. K. NEFKENS

Keyword(s):

Perturbation Theory ◽

Cross Sections ◽

Chiral Perturbation Theory ◽

Final States ◽

Proton Target ◽

Eta Meson ◽

Chiral Perturbation ◽

Crystal Ball ◽

Total Cross Sections ◽

Upper Limits

Differential and total cross sections are presented for π-- and K--induced reactions on a proton target leading to all-neutral final states. Also shown are rates for rare and upper limits for forbidden eta-meson decays to test Chiral Perturbation Theory, the π0π0 interactions and C and CP invariance.

Download Full-text

A Technique for Reliably Preparing Full-Length Metallographic Cross-Sections of Integrated Circuit Bond Wires

ISTFA 2006: Conference Proceedings from the 32nd International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa2006p0268 ◽

2006 ◽

Author(s):

Carl Nail

Keyword(s):

Integrated Circuits ◽

High Precision ◽

Cross Sections ◽

Integrated Circuit ◽

Radiographic Analysis ◽

Good Resolution ◽

Metallographic Preparation ◽

Bond Wires ◽

Darkfield Imaging ◽

Bond Wire

Abstract To overcome the obstacles in preparing high-precision cross-sections of 'blind' bond wires in integrated circuits, this article proposes a different technique that generates reliable, repeatable cross-sections of bond wires across most or all of their lengths, allowing unencumbered and relatively artifact-free analysis of a given bond wire. The basic method for cross-sectioning a 'blind' bond wire involves radiographic analysis of the sample and metallographic preparation of the sample to the plane of interest. This is followed by tracking the exact location of the plane on the original radiograph using a stereomicroscope and finally darkfield imaging in which the wire is clearly visible with good resolution.

Download Full-text

Multi-anode resistive wire proportional counter as a focal plane detector

Nuclear Instruments and Methods ◽

10.1016/0029-554x(80)90009-9 ◽

1980 ◽

Vol 171 (1) ◽

pp. 61-66 ◽

Cited By ~ 8

Author(s):

K. Iwatani ◽

H. Yokomizo ◽

M. Tanaka ◽

S. Kato ◽

T. Hasegawa ◽

...

Keyword(s):

Proportional Counter ◽

Focal Plane ◽

Plane Detector ◽

Focal Plane Detector

Download Full-text

A spectrometer focal plane detector for heavy ions

Nuclear Instruments and Methods ◽

10.1016/0029-554x(72)90292-3 ◽

1972 ◽

Vol 104 (1) ◽

pp. 21-32 ◽

Cited By ~ 54

Author(s):

B.G. Harvey ◽

J. Mahoney ◽

F.G. Pühlhofer ◽

F.S. Goulding ◽

D.A. Landis ◽

...

Keyword(s):

Focal Plane ◽

Heavy Ions ◽

Plane Detector ◽

Focal Plane Detector

Download Full-text

HIGGS PRODUCTION IN ASSOCIATION WITH BOTTOM QUARKS AT HADRON COLLIDERS

Modern Physics Letters A ◽

10.1142/s0217732306019256 ◽

2006 ◽

Vol 21 (02) ◽

pp. 89-109 ◽

Cited By ~ 56

Author(s):

S. DAWSON ◽

C. B. JACKSON ◽

L. REINA ◽

D. WACKEROTH

Keyword(s):

Standard Model ◽

Cross Sections ◽

Hadron Collider ◽

Distribution Functions ◽

Bottom Quarks ◽

Final States ◽

Leading Order ◽

Hadron Colliders ◽

Parton Distribution Functions ◽

Model Case

We review the present status of the QCD corrected cross-sections and kinematic distributions for the production of a Higgs boson in association with bottom quarks at the Fermilab Tevatron and CERN Large Hadron Collider. Results are presented for the Minimal Supersymmetric Standard Model where, for large tan β, these production modes can be greatly enhanced compared to the Standard Model case. The next-to-leading order QCD results are much less sensitive to the renormalization and factorization scales than the lowest order results, but have a significant dependence on the choice of the renormalization scheme for the bottom quark Yukawa coupling. We also investigate the uncertainties coming from the Parton Distribution Functions and find that these uncertainties can be comparable to the uncertainties from the remaining scale dependence of the next-to-leading order results. We present results separately for the different final states depending on the number of bottom quarks identified.

Download Full-text