Tagger and Beam Line R&D Three-Year Plan

 

Tagger

 

The tagging spectrometer is a QDD configuration of magnets which is used to analyze the energy-degraded electrons from the photon radiator and provide a quasi-monochromatic photon beam between the energies of 3.0 and 11.4 GeV.  The electron energies are measured along a 10m focal plane whose average intrinsic momentum resolution is 0.05% of the end-point energy.  The focal plane instrumentation consists of two hodoscopes, one comprised of 141 channels covering the complete momentum range 0.25 – 0.95 E0 and the other (the microscope) comprised a two-dimensional array of scintillating fibers subtending a segment of 5% E0  positioned around the primary coherent bremsstrahlung peak.  The horizontal segmentation of the microscope provides tagged energy channels of approximately 8 MeV width, while the vertical segmentation provides bremsstrahlung angle collimation at the focal plane that is complementary to the photon beam collimation.

Stage one R&D

 

Stage one R&D consists of the construction of a prototype segment of the microscope consisting of 5x8 array of scintillating fibers coupled by means of clear light fibers to silicon photomultiplier detectors.  A design for a prototype circuit board will be developed on which the SiPM detectors will be mounted, which will have on-board generation of the 50V bias for the SiPM’s, signal preamplifiers and multiplexing circuitry.  Experience gained with the microscope prototype will be useful in specifying the final design for the fixed-array hodoscope, so no separate prototyping for those detectors are envisaged at this stage.

Goals and Milestones

  1. Design and fabricate of two prototype SiPM readout boards.
  2. Order 40 SiPM’s for prototype tests
  3. Design and manufacture the prototype mounting frame
  4. Bench tests of SiPM readout with an LED pulser, checking light transmission and optical coupling, and testing the multiplexing circuitry.
  5. Integrate bench setup with standard GlueX data acquisition setup
  6. Beam tests with the Hall B tagger.

Personnel

  1. University of Connecticut: Richard Jones is overall P.I. on microscope R&D projects; Connecticut students will provide labor for fabrications and tests; the Physics machine shop (two full-time machinists) is available at no cost to members of the department; one electrical technician for consultation.
  2. University of Glasgow: Guangliang Yang (GlueX postdoc) and other GlueX collaboration members; circuit board design experts in the group are available for consultation.
  3. Catholic University of America: members of the GlueX collaboration and students will organize Hall B beam tests.

Photon Beam

 

The principal components of the GlueX photon beam line that require R&D are the diamond crystals for the coherent bremsstrahlung source, the photon beam active collimator, and the silicon microstrip detector for the photon beam polarimeter.

Stage one R&D

 

Stage one R&D regarding diamonds must address the mechanical integrity of very thin diamond wafers following the grinding process.  It must also address how these diamonds can be mounted to provide sufficient mechanical stability for GlueX.  It is important to investigate the effects of electron beam radiation damage and determine the effective lifetime of a crystal under the conditions of GlueX running, but that will require a significant amount of coordination with other facilities and should therefore be deferred to stage two.  The active collimator must be tested in the laboratory, and then tested in the coherent bremsstrahlung beam line in Hall B.  The existing silicon microstrip polarimeter in Hall B provides a sufficient platform for testing the GlueX polarimetry concept.  Incremental improvements to this device during the R&D phase of GlueX are envisioned, that will verify that the expected linear polarization from the coherent bremsstrahlung source can be attained at greater than half the end-point energy.

Goals and Milestones

  1. Explore what diamond diagnostics are possible using the X-ray crystallography facility at the University of Connecticut
  2. Identify any issues that require running at a synchrotron X-ray source and arrange for tests at one of the North American light sources.
  3. Develop shape deformation diagnostics for thin diamonds based upon optical and X-ray techniques.
  4.  Try out different ideas for mounting thin diamonds, and measure the stability using optical interferometry.
  5. Assemble the components of the prototype active collimator and verify the current sensitivity of the readout on the laboratory bench.
  6. Install the active collimator prototype in Hall B and measure its sensitivity during polarized photon beam running.
  7. Measure the polarization of the coherent bremsstrahlung beam in Hall B using the existing pair spectrometer and a silicon microstrip polarimeter, and compare with the calculated polarization based upon coherent spectrum analysis.

Personnel

  1. University of Connecticut: Richard Jones and Connecticut students will provide labor for crystal diagnostic measurements and data analysis; the X-ray crystallography facility technician will assist with familiarizing experimenters with this equipment; the Connecticut group is responsible for the active collimator R&D project and associated beam tests.
  2. University of Glasgow: Guangliang Yang (GlueX postdoc) is the overall P.I. on diamond crystal R&D.  Other members of the Glasgow group will assist with measurements and interpretation of results.
  3. Catholic University of America: Franz Klein is the overall P.I. on the polarimetry R&D project; members of the Catholic University group will take part in beam tests and data analysis.

 

Costs: total 3-year budget

 

description

number

units

cost / unit

total cost

postdoc salary

132

m-w

65.0 k$

195.0 k$

postdoc travel to meetings

6

trip to US

2.5 k$

15.0 k$

postdoc travel for R&D

6

to Jlab/CT

4.0 k$

24.0 k$

diamond crystals

6

wafers

4.0 k$

24.0 k$

X-ray facility use

500

hours

50 $

25.0 k$

student labor (active collimator)

9

m-w

500 $

4.5 k$

materials (active collimator)

 

supplies

 

3.0 k$

electronics (active collimator)

4

pA amp

2.0 k$

8.0 k$

student labor  (hodoscope)

60

m-w

500 $

30.0 k$

materials (hodoscope)

 

supplies

 

13.0 k$

SiPM detectors (hodoscope)

40

1mm2 SiPM

150 $

6.0 k$

electronic parts (hodoscope)

 

supplies

 

4.5 k$

FADC (hodoscope)

1

ADC unit

4.0 k$

4.0 k$

prototype circuit manufacturing

2

pcb

500 $

1.0 k$

F1 TDC (hodoscope)

1

TDC unit

4.0 k$

4.0 k$

shipping for beam tests

2

JLab/UConn

500 $

1.0 $

silicon microstrips (polarimeter)

3

planes

3.1 k$

9.3 k$

DAQ setup for beam tests

1

crate, boards

12.0 k$

12.0 k$

 

 

 

 

383.3 k$

 

 

 

 

Costs: breakdown by year and institution

Year 1: University of Glasgow

 

description

number

units

cost / unit

total cost

postdoc salary

1

44 m-w

65.0 k$

65.0 k$

postdoc travel to meetings

2

trip to US

2.5 k$

5.0 k$

postdoc travel for R&D

2

to Jlab/CT

4.0 k$

8.0 k$

diamond crystals

2

wafers

4.0 k$

8.0 k$

 

 

 

 

86 k$

Year 1: University of Connecticut [1]

 

description

number

units

cost / unit

total cost

X-ray facility use at UConn

100

hours

50 $

5.0 k$

student labor (active collimator)

9

m-w

500 $

4.5 k$

materials (active collimator)

 

supplies

 

3.0 k$

student labor (hodoscope)

15

m-w

500 $

7.5 k$

materials (hodoscope)

 

supplies

 

1.0 k$

 

 

 

 

21.0 k$

 

 

 

 

Year 2: University of Glasgow

 

description

number

units

cost / unit

total cost

postdoc salary

1

44 m-w

65.0 k$

65.0 k$

postdoc travel to meetings

2

trip to US

2.5 k$

5.0 k$

postdoc travel for R&D

2

to Jlab/CT

4.0 k$

8.0 k$

diamond crystals

2

wafers

4.0 k$

8.0 k$

 

 

 

 

86 k$

Year 2: University of Connecticut

 

description

number

units

cost / unit

total cost

X-ray tests at UConn / elsewhere

200

hours

50 $

10.0 k$

electronics (active collimator)

4

pA amp

2.0 k$

8.0 k$

student labor (hodoscope)

20

m-w

500 $

10.0 k$

materials (hodoscope)

 

supplies

 

6.0 k$

SiPM detectors

20

1mm2 SiPM

150 $

3.0 k$

electronic parts (hodoscope)

 

supplies

 

1.5 k$

FADC (hodoscope)

1

ADC unit

4.0 k$

4.0 k$

prototype circuit manufacturing

2

pcb

500 $

1.0 k$

 

 

 

 

43.5 k$

Year 2: Catholic University of America

 

description

number

units

cost / unit

total cost

silicon microstrip chips

3

planes

3.1 k$

9.3 k$

 

 

 

 

9.3 k$

 

 

Year 3: University of Glasgow

 

description

number

units

cost / unit

total cost

postdoc salary

1

44 m-w

65.0 k$

65.0 k$

postdoc travel to meetings

2

trip to US

2.5 k$

5.0 k$

postdoc travel for R&D

2

to Jlab/CT

4.0 k$

8.0 k$

diamond crystals

2

wafers

4.0 k$

8.0 k$

 

 

 

 

86 k$

Year 3: University of Connecticut

 

description

number

units

cost / unit

total cost

X-ray tests at UConn / elsewhere

200

hours

50 $

10.0 k$

student labor (hodoscope)

25

m-w

500 $

12.5 k$

materials (hodoscope)

 

supplies

 

6.0 k$

SiPM detectors

20

1mm2 SiPM

150 $

3.0 k$

F1 TDC (hodoscope)

1

TDC unit

4.0 k$

4.0 k$

electronic parts (hodoscope)

 

supplies

 

3.0 k$

shipping for beam tests

2

JLab/UConn

500 $

1.0 $

 

 

 

 

39.5 k$

Year 3: Catholic University of America

 

description

number

units

cost / unit

total cost

test boards + software

1

 

12.0 k$

12.0 k$

 

 

 

 

12.0 k$

 


[1] Costs incurred by Catholic University collaborators for beam tests will be shared from the University of Connecticut request for year 1.