Pair spectrometer hodoscope for Hall D at Jefferson Lab

Abstract

We present the design of the pair spectrometer hodoscope fabricated at Jefferson Lab and installed in the experimental Hall D. The hodoscope consists of thin scintillator tiles; the light from each tile is collected using wave-length shifting fibers and detected using a Hamamatsu silicon photomultiplier. Light collection was measured using relativistic electrons produced in the tagger area of the experimental Hall B.

Searching for Hybrid Mesons with GlueX

“…The beam is incident on 75 µm thick Beryllium radiator, after which electron-position pair conversions g + Be ! e + e +(Be) are measured in the two-armed Pair Spectrometer (PS) [4], to determine the flux and energy spectrum of the beam. An example of the electron-positron pair spectrum measured in the PS before acceptance corrections from 2016 data is shown in the top panel of Fig.…”

Measurement of the beam asymmetry Σ for π0 and η photoproduction on the proton at EγGhoul1, Anassontzis2, Austregesilo3 et al. 2017Phys. Rev. CSelf Cite685810View full textAdd to dashboardCite

“…Therefore, after the photons travel through a 75 m-long vacuum beamline, they pass through a 3.4 mm-diameter collimator, where the off-axis photons are removed, increasing the fraction of coherently produced photons. The energy of the photon beam is monitored using e + e − pair conversion from a thin (75 µm) beryllium foil downstream of the collimator, where the e + and e − energies are measured in a pair spectrometer system consisting of a dipole magnet and a pair of scintillator counter arrays [11]. The normalized photon beam energy spectra, as measured by the pair spectrometer (not corrected for instrumental acceptance), are shown in Fig.…”

Commissioning of the Pair Spectrometer of the GlueX experiment

“…The photon beam flux and the spectrum of the collimated photon beam is measured by the pair spectrometer [3], which is positioned in front of the GlueX detector. The energy of a beam photon and, therefore the beam energy spectrum, can be reconstructed by measuring the momentum of the e ± pair produced in a thin (~10 -3 radiation lengths) converter.…”

“…In order to increase the fraction of linearly polarized photons, the beam is passed through a collimator with the typical diameter of 3.5 -5 mm. Collimated photons are sent to the GlueX liquid hydrogen target.The photon beam flux and the spectrum of the collimated photon beam is measured by the pair spectrometer [3], which is positioned in front of the GlueX detector. The energy of a beam photon and, therefore the beam energy spectrum, can be reconstructed by measuring the momentum of the e ± pair produced in a thin (~10 -3 radiation lengths) converter.…”