scholarly journals Spin Physics with Photons — Technical Highlights and Spin-Offs

2016 ◽  
Vol 40 ◽  
pp. 1660064
Author(s):  
A. Thomas
Keyword(s):  
Nuclear Physics ◽  
Superconducting Magnets ◽  
Fundamental Property ◽  
Real Photon ◽  
Final States ◽  
Polarized Beams ◽  
Polarized Target ◽  
Angular Acceptance ◽  
Spin Polarized ◽  
Large Acceptance

The spin, as a fundamental property of a particle, has been a main object of investigation in particle and nuclear physics research in recent decades. For complete spin investigation, one requires a polarized target in addition to polarized beams and a recoil polarimeter. The advent of advanced beam and large acceptance detector technologies has driven the development of highly polarized, full angular acceptance targets. The Crystal Ball detector with its unique capability to cope with multi photon final states is used in Mainz at the A2 real photon facility in combination with a frozen spin polarized target. Technical highlights from the development of thin superconducting magnets to provide a longitudinal and transverse polarization are presented. A continuous polarization in the ‘DNP’-mode is on the way. Another promising technology investigation is going in the direction of ‘Active Polarized Targets’ to use the target as an intrinsic part of the detector. This requires from the scintillating material and front-end electronics to operate at cryogenic temperatures.

scholarly journals Beam Asymmetries from Light Scalar Meson Production on the Proton at GlueX

2020 ◽  
Vol 1643 (1) ◽  
pp. 012169
Author(s):  
Stuart Fegan
Keyword(s):  
Scalar Meson ◽  
Meson Production ◽  
Real Photon ◽  
Final States ◽  
Ongoing Research ◽  
Beam Asymmetry ◽  
Strong Force ◽  
Beam Asymmetries ◽  
Light Scalar ◽  
Large Acceptance

Abstract The GlueX facility, featuring a linearly polarised 9 GeV real photon beam delivered to a large-acceptance detector system, has recently completed its first phase of running, and analysis efforts of this dataset are well underway. It has been suggested that at GlueX energies, quark systems beyond the three quark and quark-antiquark systems of baryons and mesons, such as hybrid mesons, tetraquarks and glueballs, should exist, and studies of these systems could shed new light on how quarks combine under the strong force, particularly the role played by gluons. Meticulous study of the spectrum of hadronic states is required to understand the strong force in the non-perturbative energy regime, and the light scalar meson sector is an area that remains poorly understood. GlueX data encompasses final states at energies where photoproduction of the a0 (980) and f 0 (980) mesons can provide discriminatory evidence between various models, manifested in experimental observables such as the cross section and beam asymmetry, and performing detailed measurements of these quantities is considered a priority of the ongoing research program. The work presented showcases efforts to measure the beam asymmetry of the reaction γp→pηπ whose mass spectrum encompasses several mesons, including the a 0(980) light scalar, and the a 2(1320) tensor. Future prospects for related analyses in the light scalar meson sector, informed by this measurement, will also be discussed.

scholarly journals Siberian Snakes, Figure-8 and Spin Transparency Techniques for High Precision Experiments with Polarized Hadron Beams in Colliders

Symmetry ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 398
Author(s):  
Yaroslav S. Derbenev ◽  
Yury N. Filatov ◽  
Anatoliy M. Kondratenko ◽  
Mikhail A. Kondratenko ◽  
Vasiliy S. Morozov
Keyword(s):  
High Precision ◽  
High Energy Physics ◽  
High Efficiency ◽  
High Energy ◽  
Polarized Beams ◽  
Polarization Control ◽  
Spin Polarized ◽  
High Flexibility ◽  
Spin Flips ◽  
Energy Physics

We present a review of the possibilities to conduct experiments of high efficiency in the nuclear and high energy physics with spin-polarized beams in a collider complex, configuration of which includes Siberian snakes or figure-8 collider ring. Special attention is given to the recently elicited advantageous possibility to conduct high precision experiments in a regime of the spin transparency (ST) when the design global spin tune is close to zero. In this regime, the polarization control is realized by use of spin navigators (SN), which are compact special insertions of magnets dedicated to a high flexibility spin manipulation including frequent spin flips.

scholarly journals Recent results from the CBELSA/TAPS experiment at ELSA

2020 ◽  
Vol 241 ◽  
pp. 01001
Author(s):  
Farah Afzal
Keyword(s):  
Final States ◽  
Excitation Spectra ◽  
Unpolarized Cross Section ◽  
Polarized Target ◽  
Double Polarization ◽  
Perturbative Regime ◽  
Measured Polarization ◽  
Polarization Observables ◽  
The Impact ◽  
Photoproduction Reactions

In order to gain a better understanding of the dynamics inside the nucleon and of the non-perturbative regime of QCD, the nucleon excitation spectra and the properties of nucleon resonances are investigated. An essential experimental tool to achieve this goal is the study of different photoproduction reactions. Partial wave analyses are performed in order to obtain information about the contributing resonances. A complete experiment is needed to extract the underlying amplitudes unambiguously, which requires the measurement of carefully chosen single and double polarization observables in addition to the unpolarized cross section. The CBELSA/TAPS experiment in Bonn offers the possibility to measure several polarization observables using a linearly or circularly polarized photon beam and with a longitudinally or transversely polarized target. This contribution gives an overview of recently measured polarization observables in different final states. The impact of the new data is discussed.

The history, development, and future prospects for (e,2e) spectroscopy

1996 ◽  
Vol 74 (11-12) ◽  
pp. 703-712 ◽  
Author(s):  
Ian E. McCarthy
Keyword(s):  
Nuclear Physics ◽  
Experimental Result ◽  
Particle Model ◽  
Sensitive Information ◽  
Final States ◽  
Independent Particle ◽  
Electron Momentum Spectroscopy ◽  
Independent Particle Model ◽  
Valence Bands ◽  
Momentum Space Orbitals

Electron momentum spectroscopy of atoms, molecules, and solids is based on (e,2e) reactions that observe the distribution of recoil momenta for energy-resolved states of the residual system. It is interpreted simply in terms of the momentum-space orbitals of the independent-particle model. The relevant ideas originated in nuclear physics. The earliest experiments observed that strongly excited final states belong to orbital manifolds that extend the independent-particle ideas to correlated systems. Some weakly excited final states do not belong to orbital manifolds. They give sensitive information about target ground-state correlations. The energy-momentum distribution of valence bands is observed for solids. Calculations for atoms, molecules, and crystals converge to the experimental result as the structure calculation is improved.

Antihydrogen atom formation in a CUSP trap towards spin polarized beams

LEAP 2011 ◽  
2012 ◽  
pp. 31-40
Author(s):  
N. Kuroda ◽  
Y. Enomoto ◽  
K. Michishio ◽  
C. H. Kim ◽  
H. Higaki ◽  
...  
Keyword(s):  
Antihydrogen Atom ◽  
Polarized Beams ◽  
Spin Polarized

RECENT RESULTS FROM THE REAL PHOTON EXPERIMENT AT MAMI

2010 ◽  
Vol 19 (05n06) ◽  
pp. 1064-1075
Author(s):  
ANDREAS THOMAS
Keyword(s):  
High Intensity ◽  
Photon Beam ◽  
Real Photon ◽  
Final States ◽  
Detection Capability ◽  
Crystal Ball ◽  
The Real ◽  
The Future ◽  
Set Up

Experiments with real photons have been performed for many years at the Mainz accelerator MAMI with different detectors. The upgraded MAMI C accelerator recently delivered electrons with an energy of 1604MeV. The A2 collaboration performs experiments with energy tagged polarised real photons produced via 'Bremsstrahlung'. Linear and circular photon polarisation is possible. In the years 2005/2006 the Crystal Ball detector with its unique detection capability for multi photon final states was set up in Mainz. The Crystal Ball at MAMI setup offers an excellent possibility to study decays of the η and η′ mesons. Due to the high intensity photon beam the apparatus can be seen as an η-factory. Recent results from the Crystal Ball experiment at MAMI are presented. In the future we plan to use a longitudinal and transverse polarised frozen spin target to investigate the spin polarisibilities of the nucleons.

Antihydrogen atom formation in a CUSP trap towards spin polarized beams

2012 ◽  
Vol 212 (1-3) ◽  
pp. 31-40
Author(s):  
N. Kuroda ◽  
Y. Enomoto ◽  
K. Michishio ◽  
C. H. Kim ◽  
H. Higaki ◽  
...  
Keyword(s):  
Antihydrogen Atom ◽  
Polarized Beams ◽  
Spin Polarized

OVERVIEW OF EXPERIMENTAL RESULTS FROM HERMES

2012 ◽  
Vol 20 ◽  
pp. 19-28
Author(s):  
MARCO CONTALBRIGO
Keyword(s):  
Degrees Of Freedom ◽  
Distribution Functions ◽  
Real Photon ◽  
Final States ◽  
Spin Orbit ◽  
Parton Distribution Functions ◽  
Transverse Momentum Dependent ◽  
Hermes Experiment ◽  
Electrons And Positrons ◽  
Azimuthal Asymmetries

The investigation of the partonic degrees of freedom beyond collinear approximation (3D description) has been gained increasing interest in the last decade. At the HERMES experiment, azimuthal asymmetries in hard exclusive reactions and in semi-inclusive deep-inelastic scattering of electrons and positrons off a (polarized) hydrogen and deuterium target have been measured. Such asymmetries provide new insights on crucial aspects of the parton dynamics. By measuring various hadron types in the initial and final states, flavor sensitivity is achieved. Non zero signals are reported for azimuthal asymmetries with respect the transverse target polarization in real-photon exclusive-electroproduction, which are related (still in a model dependent way) to the elusive quark orbital motion. Evidence is reported of the poorly known transversity function and of naive-T-odd transverse-momentum-dependent parton distribution functions related to spin-orbit effects. Evidence of spin-orbit effects in quark fragmentation is also observed, which are opposite in sign for favored and disfavored processes.

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