TJNAF HALL A HRS DETECTOR SYSTEMS

VDCs:

• 368 wires per plane / 4 planes per spectr. (UV + UV)
• 2944 wires total for both spectrometers
• no guard wires
• UV wire orientation (45 degrees relative to frame)
• 4.23 mm wire spacing (6 mm along frame edge)
• 20um Au plated Tungsten sense wires

	   The wire spacing is 6 mm along the frame edge which translates to
	   4.24 mm perpendicular distance between wires. The distance from
	   H.V. plane to H.V. plane is 1 inch = 25.4 mm.  The projection of
	   the track into the wire plane and within the gas volume is
	   therefore L = 25.4 mm/tan(theta) = 19.6 to 32.9mm long. Since the
	   wires are oriented at 45 degrees relative to X and Y this track
	   will intercept L/(sqrt(2)x4.24) = 3.3 to 5.5 cells.

Electron Arm Scintillators:

• 2 double-ended planes with segmentation 6,6
• • 6+6=12 counters / 24 Photomultiplier tubes (2 inch tubes)
• Bicron BC-408 Plastic
  • Polyvinyltoluene (PVT) is the base material
  • Light output is 64% that of Anthracene
  • Wavelength of maximum emission is 425 nm
  • Decay constant of the main fluorescence component is 2.1ns
  • Bulk attenuation length is 380 cm
  • Index of refraction is 1.58
  • Density is 1.032
  • Softening Point is 70deg C
• Edges of counters will be overlapped for Planes 1 and 2.

• 6 counters
• PMT: Burle 8575 2" (one tube at each end)
• • Base and tube assembly 3" diameter and 9 5/8" + 4 1/4" long
• Active area: 36cm(in dispersive) x 176cm(in transverse) x 0.5cm
• Including isochronous guides+lightrod: cm x 29.3cm x 0.5cm
• Including PMTs and housings: 213cm x 29.3cm x 0.5cm
• Total size of plane 1: 213cm x 176cm x 0.5cm
• Orientation: long axes (213cm) normal to the bend plane

• 6 counters
• PMT: Burle 8575 2" (one tube at each end)
• • Base and tube assembly 3" diameter and 9 5/8" + 4 1/4" long
• Active area: 54(64?)cm x 37cm x 0.5cm
• Including adiabatic guides+lightrod: 178cm x 37cm x 0.5cm
• Including PMTs and housings: 231cm x 37cm x 0.5cm
• Total size of plane 2: 231cm x 222cm x 0.5cm
• Orientation: long axes (231cm) normal to the bend plane

Hadron Arm Scintillators:

• 3 double-ended planes with segmentation 6,6,9
• 6+6+9=21 counters / 42 Photo tubes (24 two-inch and 18 five-inch)
• Bicron BC-408 Plastic
• Edges of counters will be overlapped for Planes 1 and 2.
• Plane 3 will not be overlapped due to type of construction.

• same as for electron arm (including location and sizes)

• Sizes same as Plane 2 of electron arm

• 9 counters
• PMT: Burle 8854 5" (one at each end of each segment)

•        Notes:8854-37 indicates electrical selection of
  	less than 2500 dark counts per second and peak to
  	valley ratio greater than 1.2.  Tubes culled out of order
  	of 40 tubes shipped in '92.
  	Glass is Schott 8337, similar to Corning 9741.
  	Striations on glass are claimed by Burle to be
  	some aging affect of the glass prior to assembly
  	by Burle.

• Active area: 155cm x 40cm x 2.0cm
• Including adiabatic guides+lightrod: 297cm x 40cm x 2.0cm
• Including PMTs and housings: 381cm x 40cm x 2.0cm
• Total size of plane 3: 381cm x 360cm x 2.0cm
• Orientation: long axes (381cm) normal to the bend plane

Aerogel Cerenkov:

• Active SiO2 detector dimensions: 195cm x 41cm x 7 (or 9)cm
• Physical enclosure dimensions: 196.2cm x 126.7cm x 36.3cm (includes PMT housings)
• Approximate weight: 175*2 = 250lbs
• PMT: Burle 8854 5" (one at both ends of each of 13 segments)
  • 26 PMTs per spectrometer * 2 = 52 PMTs
• Index of refraction: 1.025
• Length of radiator: 7-9 cm of silica aerogel

Gas Cerenkov:

• Thicknesses of materials:
  • Entrance window: 1.5mil PVF (Charcoal Tedlar)
  • Gas: 1.5m(e- arm)/1m(hadron arm) CO2 at atm
  • Mirrors: ten spherical with 90cm radius of curvature
    • 40nm MgF2
    • 80nm Al
    • 1mm lucite
    • 0.2mm carbon-epoxy
    • 10mm phenol honeycomb
    • 0.2mm carbon-epoxy
  • Exit window: 1.5mil PVF (Charcoal Tedlar)
  • 10 PMTs per spectrometer * 2 = 20 PMTs:
    • Burle 8854 - one per mirror (66ns transit time)
• Location in electron arm:
  • Between aerogel and scintillator plane 2
• Location in hadron arm:
  • Between 1st and 2nd polarimeter chambers
• Counter sizes (nominal)
  • Both electron and hadron arm counters assumed identical except for length.
    • Transverse: +/- 250mm active (1193mm(w/ PMT) total)
    • Dispersive: mm active (2547mm total)
• Gas connection required.
  • 1 of 1/2 inch for input per arm ( 2 total )
  • 1 of 1/2 inch for output per arm ( 2 total )

Shower Counters:

• Yerevan TF-1 glass:
  • Radiation length: 2.74cm
  • Refractive index: 1.647
  • Density: 3.86 g/cm^3
• PMTs: Hammamatsu R3036 three inch with mu-metal shields
• Pairs of blocks touching end to end, mounted transverse to central ray.
• Array of 2x24 long blocks gives area: 700mm x 2400mm

• bought from CERN-UA2
• Schott SF5 glass:
  • Radiation length: 2.38cm
  • Refractive index: 1.6727 (587.6nm wavelength) 1.7107 (404.7nm wavelength)
  • Density: 4.08 g/cm^3
• PMTs: Philips XP2050 five inch without mu-metal shields
• Blocks mounted longitudinally (parallel to central ray)
• Array of 6x16 blocks gives area: 900mm x 2400mm

	  When mounting the box containing Plane 2 it should be lifted at a 30 
	     degree angle to the horizontal.  Lifting bolts in box are 4.5"OD
	     with a 1" diameter ring.  2" diameter shoulder on it.  Rating is
	     13000lbs in a straight lift.  At a 45 degree lift it is
	     13000*.3=3900lbs.
	     Approximate weight of loaded box is 8300lbs.

Focal Plane Polarimeter:

• 5 straw-tube wire planes
• SC1 and SC2 surround the gas Cerenkov counter.
  • 5200 channels / 5 chambers