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Title: SUITABILITY OF A NEW CALORIMETER FOR EXOTIC MESON SEARCHES

Abstract

Exotic mesons, particles that have quantum numbers that are inaccessible to conventional quark-model mesons, are predicted by quantum chromodynamics (QCD), but past experiments seeking to identify exotic candidates have produced controversial results. The HyCLAS experiment (E04005) at Thomas Jefferson National Accelerator Facility (TJNAF) proposes the use of the Continuous Electron Beam Accelerator Facility (CEBAF) Large Acceptance Spectrometer (CLAS) in Hall B to study the photoproduction of exotic mesons. However, the base detector package at CLAS is not ideal for observing and measuring neutral particles, particularly at forward angles. The Deeply Virtual Compton Scattering (DVCS) experiment at TJNAF has commissioned a new calorimeter for detecting small-angle photons, but studies must be performed to determine its suitability for a meson spectroscopy experiment. The ηπ system has been under especial scrutiny in the community as a source for potential exotics, so the new calorimeter’s ability at reconstructing these resonances must be evaluated. To achieve this, the invariant mass of showers in the calorimeter are reconstructed. Also, two electroproduction reaction channels analogous to photoproduction channels of interest to HyCLAS are examined in DVCS data. It is found that, while not ideal, the new calorimeter will allow access to additional reaction channels, and its inclusionmore » in HyCLAS is warranted. Results in basic shower reconstruction show that the calorimeter has good effi ciency in resolving π° decays, but its η reconstruction is not as strong. When examining ep → epπ°η, preliminary reconstruction of the ηπ° system shows faint signals in the a0(980) region. In the ep → e n π+ η channel, preliminary reconstruction of the ηπ+ system gave good signals in the a0(980) and a2(1320) regions, but statistics were poor. While more analyses are necessary to improve statistics and remove background, these preliminary results support the claim that the DVCS calorimeter will be a valuable addition to CLAS for upcoming exotic meson searches in photoproduction.« less

Authors:
; ;
Publication Date:
Research Org.:
DOESC (USDOE Office of Science (SC) (United States))
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1051812
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Undergraduate Research; Journal Volume: 7
Country of Publication:
United States
Language:
English

Citation Formats

Bookwalter, C., Ostrovidov, A., and Eugenio, P. SUITABILITY OF A NEW CALORIMETER FOR EXOTIC MESON SEARCHES. United States: N. p., 2007. Web.
Bookwalter, C., Ostrovidov, A., & Eugenio, P. SUITABILITY OF A NEW CALORIMETER FOR EXOTIC MESON SEARCHES. United States.
Bookwalter, C., Ostrovidov, A., and Eugenio, P. Mon . "SUITABILITY OF A NEW CALORIMETER FOR EXOTIC MESON SEARCHES". United States. doi:. https://www.osti.gov/servlets/purl/1051812.
@article{osti_1051812,
title = {SUITABILITY OF A NEW CALORIMETER FOR EXOTIC MESON SEARCHES},
author = {Bookwalter, C. and Ostrovidov, A. and Eugenio, P.},
abstractNote = {Exotic mesons, particles that have quantum numbers that are inaccessible to conventional quark-model mesons, are predicted by quantum chromodynamics (QCD), but past experiments seeking to identify exotic candidates have produced controversial results. The HyCLAS experiment (E04005) at Thomas Jefferson National Accelerator Facility (TJNAF) proposes the use of the Continuous Electron Beam Accelerator Facility (CEBAF) Large Acceptance Spectrometer (CLAS) in Hall B to study the photoproduction of exotic mesons. However, the base detector package at CLAS is not ideal for observing and measuring neutral particles, particularly at forward angles. The Deeply Virtual Compton Scattering (DVCS) experiment at TJNAF has commissioned a new calorimeter for detecting small-angle photons, but studies must be performed to determine its suitability for a meson spectroscopy experiment. The ηπ system has been under especial scrutiny in the community as a source for potential exotics, so the new calorimeter’s ability at reconstructing these resonances must be evaluated. To achieve this, the invariant mass of showers in the calorimeter are reconstructed. Also, two electroproduction reaction channels analogous to photoproduction channels of interest to HyCLAS are examined in DVCS data. It is found that, while not ideal, the new calorimeter will allow access to additional reaction channels, and its inclusion in HyCLAS is warranted. Results in basic shower reconstruction show that the calorimeter has good effi ciency in resolving π° decays, but its η reconstruction is not as strong. When examining ep → epπ°η, preliminary reconstruction of the ηπ° system shows faint signals in the a0(980) region. In the ep → e n π+ η channel, preliminary reconstruction of the ηπ+ system gave good signals in the a0(980) and a2(1320) regions, but statistics were poor. While more analyses are necessary to improve statistics and remove background, these preliminary results support the claim that the DVCS calorimeter will be a valuable addition to CLAS for upcoming exotic meson searches in photoproduction.},
doi = {},
journal = {Journal of Undergraduate Research},
number = ,
volume = 7,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}
  • The authors analyze the processes {rvec {gamma}} + p {r_arrow} {rho}{sup 0}{pi}{sup +}n at low momentum transfer focusing on a possibility of production of an exotic J{sup PC} = 1{-+} meson state. In particular they discuss polarization observables and conclude that linear photon polarization is instrumental for separating of the exotic wave.
  • The results of searches for various exotic objects at PETRA during 1982 and 1983 are summarized. No evidence is found for these exotic objects. New results of an energy scan for the top quark are presented. Results on the fragmentation functions and branching ratios of heavy quarks from the study of inclusive muon spectra are presented.
  • The decay {sup 187}Re(5/2{sup +}) {r_arrow} {sup 187}Os{1/2}{sup -} + e{sup -} + {anti v}{sub e}, Q{sub {Beta}-}=2.6 keV, t{sub {1/2}} = 4.3 x 10{sup 10} yrs, may be studied in a superconducting Re absorber operating at temperatures of {approximately} 0.1 Kelvin. The temperature transient, in principle, can provide a high resolution ({approximately} 5 eV FWHM) measure of the total energy not given to the {anti v}{sub e} of individual beta decays. The technique avoids the practical problems of energy loss in the source, slit scattering, and variation in detection efficiency as well as the theoretical question of final states.more » However, the necessity of viewing the entire spectrum raises the question of the statistical accuracy achievable in a practical experiment. By Monte Carlo study, including the effects of pileup and background and the measurement of the resolution function, we demonstrate that, theoretically, a single device can reach a precision of 60 eV{sup 2} (1 {sigma}) or 10 eV (95% C.L.), assuming a central value of zero, in 50 days and that 16 such detectors could reach a 5 eV limit in the same time.« less
  • No abstract prepared.