PIONIC FUSION AT SUBTHRESHOLD ENERGIES

2009 ◽  
Vol 24 (02n03) ◽  
pp. 539-543
Author(s):  
L. JOULAEIZADEH ◽  
J. BACELAR ◽  
M. ESLAMI-KALANTARI ◽  
I. GAŠPARIĆ ◽  
N. KALANTAR-NAYESTANAKI ◽  
...  
Keyword(s):  
Cross Sections ◽  
Pion Production ◽  
Detection System ◽  
Nucleon Nucleon ◽  
Accelerator Facility ◽  
Production Threshold ◽  
Neutral Pions ◽  
Pion Production Threshold ◽  
Plastic Ball ◽  
Large Acceptance

In order to study the role of pions and clustering phenomena in nuclei, two experiments have been performed using the AGOR accelerator facility. In collisions of two nuclei a pion and a fused nucleus were produced. The examined reactions were 4He(3He, π0)7Be and 6Li(4He, π0)10B at beam energies about 10 MeV above the coherent pion production threshold (256 MeV and 236.4 MeV, respectively). Since the available energy is well below the pion production threshold in an elementary nucleon-nucleon process, a highly coherent mechanism is needed. We identified the reaction by measuring the fused system in the magnetic spectrometer and the produced neutral pions in the Plastic Ball detection system with large acceptance. Our experimental setup provided the exclusive cross sections by identifying all products in overdetermined kinematics. Here we present the preliminary results of the analysis for the second reaction. Angular distribution of neutral pions will be discussed.

Forward p(n,d)γ cross sections above the pion production threshold

1992 ◽  
Vol 543 (4) ◽  
pp. 685-702 ◽  
Author(s):  
G.W.R. Edwards ◽  
R. Abegg ◽  
M. Ahmad ◽  
J.M. Cameron ◽  
G.H. Coombes ◽  
...  
Keyword(s):  
Cross Sections ◽  
Pion Production ◽  
Production Threshold ◽  
Pion Production Threshold

scholarly journals Double polarisation observable E and helicity dependent cross section for single π0 photoproduction off proton and neutron

2020 ◽  
Vol 241 ◽  
pp. 01005
Author(s):  
Susanna Costanza ◽  
Federico Cividini
Keyword(s):  
Cross Sections ◽  
Pion Production ◽  
Photon Beam ◽  
Reaction Products ◽  
Meson Photoproduction ◽  
Production Threshold ◽  
Resonance Properties ◽  
Large Acceptance ◽  
Polarised Beams

Photon-induced reactions, like meson photoproduction, allow to excite the nucleon, to have access to many different polarisation observables and are an essential tool to disentangle the role of the different electromagnetic multipoles due to the change of sign of some contributions and the presence of interference terms between different multipole amplitudes. In addition, the use of polarised beams and/or targets allow to access additional observables which are fundamental in order to accurately determine the nucleon resonance properties. The A2@MAMI collaboration is carrying out a broad and systematic study on this topics, both on the proton and the neutron. The experiments are performed at the tagged photon beam facility of the MAMI accelerator in Mainz, using circularly and linearly polarised photons on longitudinally polarised proton and deuteron targets, for energies ranging from the pion production threshold up to 1.6 GeV. Hadronic reaction products are then measured with the large acceptance Crystal Ball spectrometer, complemented by charged particle and vertex detectors for tracking and identification. An overview of the results obtained so far for the double polarisation observable E (circularly polarised photon beam on a longitudinally polarised target) on the single π0 photoproduction off the proton and the neutron will be given. Furthermore, new results on the helicity-dependent total and differential cross sections on the deuteron will be presented.

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