Transcript Gas Ring Imaging Cherenkov (GRINCH) Detector for BigBite Abdellah Ahmidouch and Samuel Danagoulian Department of Physics NC A&T State University, Greensboro, NC Todd Averett, H.

Gas Ring Imaging Cherenkov
(GRINCH) Detector for BigBite
Abdellah Ahmidouch and Samuel Danagoulian
Department of Physics
NC A&T State University, Greensboro, NC
Todd Averett, H. Yao, William and Mary
B. Wojtsekhowski, S. Esp, Jefferson Lab
K. Aniol, Cal. State LA
J. Annand, Glasgow
11/7/2015
SBS Collaboration Meeting.
JLAB, June 4-5, 2013
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Outline
• Motivation
• Design
• Status
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Status of the mirrors
Status of the detection array
Prototype measurements
Time scale
• Budgeting
• Summary
11/7/2015
SBS Collaboration Meeting.
JLAB, June 4-5, 2013
2
Motivation: High Rate Running
• Expect 4-5x increase in total luminosity over previous
BigBite running.
• Assume 4-5x background rate.
• 30 degree scattering angle
• Segmented PMT array (29mm tubes), 9(8) x 60 tubes
• Search for timing clusters in 5-10 ns window.
• Magnetic shielding between rows.
• Locate PMT array on large angle side away from beam
line.
• C4F8O heavy gas at 1 atm
11/7/2015
SBS Collaboration Meeting. JLAB, June 4-5,
2013
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Simulation and Design
• Design based on GEANT 4 simulation (W&M)
and geometric constraints from BigBite
detector package
• 65 cm path length, 85 cm reflected path
• Single reflection from cylindrical mirrors. Not
focusing on specific PMT’s, not sensitive to
precise mirror geometry/alignment
• Clusters with avg 10 PMT’s/event and 1.7
p.e.’s/tube
11/7/2015
SBS Collaboration Meeting. JLAB, June 4-5,
2013
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Design Update
• First version of design complete.
• Approval granted to complete full production drawings to
solicit bids. Expected June 2013.
• Detector vessel made from frame of angled aluminum with
sheet aluminum sides (Jlab)
• 9 (8) x 60 array of PMT’s in iron box, with mu metal and iron
strips/bars between rows. Attach to vessel, removable. (NC
A&T)
• Removable mirror frame, adjustable mirror mounting system.
(W&M)
11/7/2015
SBS Collaboration Meeting. JLAB, June 4-5,
2013
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Design
11/7/2015
SBS Collaboration Meeting. JLAB, June 4-5,
2013
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Mirror Frame
11/7/2015
SBS Collaboration Meeting. JLAB, June 4-5,
2013
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Mirror alignment tests
• We expect to coat flat 1/8” thick Lexan and then bend
into the correct shape by applying torque with the
mounting hardware.
• Second option, pre-formed mirror blanks that would then
be coated (thicker with backing and more expensive).
• JLab design group and W&M machine shop produced a
full size prototype of the mirror mounting system.
• We are currently measuring the geometry of a 1/8” Lexan
sheet and learning how to produce a cylindrical surface.
Cost estimate to make full mirror frame and mounts at
W&M is about $5k.
11/7/2015
SBS Collaboration Meeting. JLAB, June 4-5,
2013
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Mirror alignment tests (cont.)
Results to date:
• Functionality of mount and
adjustment is good.
• Radius of curvature is not naturally
constant across the width of the
mirror. Not unexpected.
Nonlinear.
• Learning to mechanically shape
mirror to give proper transport of
light to location of PMT array.
• Con-currently developing laser
alignment system.
11/7/2015
SBS Collaboration Meeting. JLAB, June 4-5,
2013
Mirror
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11/7/2015
SBS Collaboration Meeting. JLAB, June 4-5,
2013
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Mirror Reflectivity Tests
• Received sample of Al-coated Lexan, flat pieces,
from ECI coatings.
• H. Yao measured reflectivity in test stand in FEL
building.
Manufacturer data
11/7/2015
SBS Collaboration Meeting. JLAB, June 4-5,
2013
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Reflectivity Results
• Results not clean because:
• System designed for mirrors that focus all reflected light
onto a photodiode.
• Doesn’t work geometrically for flat mirror. Realignment of
PD required during scans.
• Still, reflectivity generally above about 86%
11/7/2015
SBS Collaboration Meeting. JLAB, June 4-5,
2013
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Continued Mirror Tests
• We measured the relative reflectivity ratio at 3 fixed
wavelengths in the visible spectrum for a sample mirror that
was first flat and then bent to the proper cylindrical radius. This
was repeated several times and no change in reflectivity within
our precision (est. 10% rel.) was observed. Successful formed
Lexan using custom made heated molds. Not optical quality.
• Successfully slumped and glued a 1’ x 1’ prototype mirror with
honeycomb and Lexan backing (similar to Hall A HRS design).
Not optical quality but proof of principle to form the correct
mirror geometry if needed prior to coating. See next slide
11/7/2015
SBS Collaboration Meeting. JLAB, June 4-5,
2013
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11/7/2015
SBS Collaboration Meeting. JLAB, June 4-5,
2013
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Front end Electronics
• J. Annand has produced phase II
prototype of NINO front-end
card.
• Successfully tested phase I card
using signals similar to expected
small-amplitude single PE signals
from GRINCH.
• K. Aniol recently completed
purchase for all NINO cards.
11/7/2015
SBS Collaboration Meeting. JLAB, June 4-5,
2013
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Plans (W&M)
• Finish production drawings for vessel, mirror mounting, July
31st, 2013
– Send drawings for quotes
– Fabrication, Fall 2013 (need Jlab approval)
– Assembly, testing, Early 2014
• Finalize mirror design studies by May 30th
– Order mirrors in summer.
• Other summer projects
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11/7/2015
Gas system
Mirror alignment system
Cables
Gain matching studies using rates/timing (with NC A&T)
HV distribution system (with NC A&T)
SBS Collaboration Meeting. JLAB, June 4-5,
2013
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Photon Detector Array (NC A&T)
 Array of 9(8)x60 29-mm PMTs
ET: 29 mm photomultiplier 9125B from
DIRC
 Housed in an iron magnetic
shielding box. Steel 1008
 Each row is shielded at the front
by two adj. 1-mm thick plates
(m-metal and iron)
 Mirrored plastic cones for light
collection (light catchers)
11/7/2015
SBS Collaboration Meeting. JLAB, June 4-5,
2013
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Photon Detector Array (cont.)
Prototype parts:
a) magnetic shielding box
b) 1 mm steel bars, made of steel-1008
c) m-metal shielding box
d) Light catchers
Prototype: 4 rows of 9(8) PMTs + reflectors + Mag. Shield box
 Assembled and tested
 the reflectors and 1 mm steel bars will be sent for
mirror deposition.
11/7/2015
SBS Collaboration Meeting. JLAB, June 4-5,
2013
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Detector Array status
• Prototyping
done (pending mirror deposition)
• PDA final design July - September 2013 (JLAB designer)
• PDA fabrication
September-November 2013
• PDA Assembly
December 2013 – January 2014
• Test of the PDA
January – March 2014
11/7/2015
SBS Collaboration Meeting. JLAB, June 4-5,
2013
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Photon Detector
Array. Prototyping
1. Light catcher
2. m-metal box
3. Prototype box with 1 mm
bars.
11/7/2015
SBS Collaboration Meeting. JLAB, June 4-5,
2013
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Photon Detector Array Prototyping
(cont.)
11/7/2015
SBS Collaboration Meeting. JLAB, June 4-5,
2013
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Photon Detector Array Prototyping
(cont.)
11/7/2015
SBS Collaboration Meeting. JLAB, June 4-5,
2013
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Prototype Testing
Configuration a,b,c
11/7/2015
SBS Collaboration Meeting. JLAB, June 4-5,
2013
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Prototype Testing
• Results of magnetic test at A&T
Configuration
Bx,y,z w/o
shielding
box
Bx,y,z at the phcathode (with
shielding box)
Comments
a (plates are
along XZ)
Bx0= 0
By0 = 0
Bz0 = 15 G
Bx= 0
By = 0
Bz = 3.5 G
(±0.2)
b
Bx0= 15 G
By0 = 0
Bz0 =0
Bx= 0
By = 1.6 G
Bz = 0
c (field is
along Y)
Bx0 = 0
By0= 15
Bz0= 0
Bx= 0
By = 0
Bz = 0
11/7/2015
z
x
SBS Collaboration Meeting. JLAB, June 4-5,
2013
y
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Prototype Testing (cont.)
• Results of magnetic test at W&M
Configuration
Bx,y,z w/o
Bx,y,z at the phshielding box cathode (with
shielding box)
Comments
z
y
x
a (plates are
along XZ)
Bx0= 0
By0 = 0
Bz0 =30.5 G
Bx= 0.4
By = 0.9
Bz = 7 G
c (plates are
along XY)
Bx0= 0
By0 = 0
Bz0 = 30.5 G
Bx= 2.0 G
By = 0
Bz = 1.2 G
11/7/2015
(±0.2)
SBS Collaboration Meeting. JLAB, June 4-5,
2013
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Prototype Testing (cont.)
The efficiency of the PMT
decreases to 90% if the
field strength in Z direction
is kept within ±7 G. In X
direction (perpendicular to
dynodes) the tolerance is
±4 G, in Y direction - ±1.5 G
11/7/2015
SBS Collaboration Meeting. JLAB, June 4-5,
2013
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Budget (A&T)
• PMT detector array:
• Magnetic Shielding Box, Steel 1008
~$6000.00
• Mu-metal shelf ~$1000.00
• Light catchers. Molding is done (~$10,000.00).
Each row is $3, we need 60 rows.
• Mirror deposition: ?
11/7/2015
SBS Collaboration Meeting. JLAB, June 4-5,
2013
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Summary
• The Gas Cherenkov (GRINCH) will be
completed and tested by Spring 2014 and
ready to install by June 2014
– Vessel, mirror mounting system, mirrors (JLAB, W&M)
– Photon Detector Array (NC A&T)
– Front electronics (Cal. State LA, Glasgow)
• Total Budget: ~$25 K (NCA&T) ~$50 K (W&M),
$10 K (Glasgow University), $50 K (JLAB)
11/7/2015
SBS Collaboration Meeting. JLAB, June 4-5,
2013
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Summary (cont.)
11/7/2015
SBS Collaboration Meeting. JLAB, June 4-5,
2013
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