Supported by 2014 JSA Postdoc Prize
Zhihong Ye
Duke University
JLab User Group Meeting, 06/03/2014
Original Motivation:
The Proton Charged Radius Experiment (PRad) in Hall-B

High resolution, large acceptance, hybrid HyCal calorimeter (PbWO4 and Pb-glass)

Measure GEp within Q2 range of 2x10-4 – 2.0x10-2 GeV2 (lower than all previous (e,p) experiments)

Simultaneous detection of elastic and Møller electrons

Windowless H2 gas flow target
Add a new position detector here
 To increase the resolution at the lowest Q2 points, we
decied to add a new position detector with additional
features:

Thin  Not too much space between Vacuum
Box Exit and HyCal

Minimum radiation materials  Control the
background events at a small level.
 Allow a hole at the center for the electron beam to
Spokesperson: A. Gasparian, D. Dutta, H. Gao, M. Khandaker
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go through
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Original Motivation:
The Proton Charged Radius Experiment (PRad) in Hall-B
 Possible Candidates of Position Detectors (or Tracking Devices):
o
Drift Chambers (DC)
• Provide <100 um position resolution; Thin; Widely used;
• No enough time to design, built and test a 1.2 meter x 1.2 meter large DC;
• Hard to produce a hole at the center;
 GEM current selection
 High tracking resolution (<100um) and good timing (~ 10ns); High rate; Insensitive to EM field
 UVa (Nilanga Liyanage’s group) can produce 120cm x 60cm plates;
 A hole can be produced;
 Can be ready before the experiment; Readout electronics are available;
 Scintillating Fiber Tracker (SFT) as a backup due to the lack of time, man-power and experience
• Good position resolution: e.g. 1mm fibers can give as good as ~300um;
• Thin, e.g. 1 mm plastic fiber gives only <0.3% radiation length;
• Replace Veto-Counter to perform precise time-measurement at the same time
• A hole can be easily produced.
• And more advantages!
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Scintillating Fiber Tracker: Advantages
 Scintillating Material: emits visible lights via de-excitation when a charged particle deposits its energy through
ionization process;
 Scintillating Fiber (SciFi): A core of scintillating materials with one or several layers of thin cladding with lower
index of refraction;
 Good Time Response: SFT can provide better timing measurement than DC and GEM;
 Without Gas Systems: Unlike GEM and DC;
 Easy Handling: Easily installed, stored and transported; can be used in vacuum or high EM field;
 Easy Analysis: We just need to determine which SciFi is fired (“YES/NO” algorithm).
This new SFT can have a wide application in many projects!
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Scintillating Fiber Tracker: Previous Developments
 Existing similar detectors (since 1990s):
 Mainly applied in Medical Imaging (small size):
e.g., Proton Computed Tomography Scanner (FERMILAB-PUB-12-067-E), INFN
 D0 in Fermi Lab: 0.84 mm SciFi + Visible Light Photon-Counter (VLPC)
Four concentric cylinders (Nucl. Phy. B 61B (1998) 384-389)
 KAOS in Mainz: 200cm wide 50cm long 0.25mm SciFi + Multi-Anode PMT
200cm x 50cm, only the vertical plane (C. Ayerbe Gayoso, PhD thesis)
by INFN
 New detectors under developing:
 LHCb: 300cm long 0.25mm round SciFi+ Silicon Photon Multiplier
250cm x 300cm, 5 super layers, only the vertical plane
 COMPASS, HERMES, SONTRAC, etc …
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Scintillating Fiber Tracker: Our Design
 The new SFT proposed for PRad:
 120cm x 120cm active area
SciFi would be about 1.5m long
Detector Frame
 X&Y position tracking on electrons
Two perpendicular planes, each has two layers of SciFi
 Time measurement on electrons
replacing veto-counter to reject photons
 A hole at the center allowing the beam pipe to go through
Photon-Detectors on one side only
For 1mm SciFi (300um resolution), ~4800 fibers and ~2400 output-channels!
(If combining two-fibers and reading out signal from one-end)
 What we should know before we build:
 What type of SciFi? How many layers?
 How to assemble the SciFi?
 How to mount the SciFi on the supporting structure?
 What type of photon-detector?
Silicon Photon Multiplier (SiPM) or Multi-Anode PMT (MaPMT) ?
 What Read-Out system?
 How to reduce the cost?
Two fibers as
one readout
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Prototype Test Project:
https://wiki.jlab.org/pcrewiki/index.php/Prototype_Test
The Plan
Propose the project
Prepare Setup
Purchase Samples
Test SciFi
Here we are!
Test SiPM
Purchase &
Assemble SciFi
 The SFT Prototype:

5 cm x 5 cm active area

50 (X) and 50 (Y) read-out channels

200 1.5 meter long SciFi

100 SiPMs

Mounting Frame and Supporting Struecture
Design Mounting
Frame
Purchase / Make
(Detectors, PS, PreAmp)
Read-Out System (FastBus, fADC, others?)
Test Tracking Performance (with beam?)
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Prototype Test Project:
The Hall-a Laser Lab shared with SoLID-EC test
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Prototype Test Project: SciFi Test
 Selection of SciFi:
 Numbers about SciFi claimed by manufactures:
 ~8000(?) photons/MeV for each MIP within a 1mm fiber;
Single-Clad
 ~3.1% Trap-Efficiency for Single-Clad (~5.4% for Multi-Clad);
 ~ 3 ns Decay Time;
 ~4 m Attenuation Length (for blue light);
 Position Resolution:
 D
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, where D is the diameter of the fiber
Multi-Clad
Considering the quantum efficiency of photon-detector (<30%), 1-mm SciFi gives <50 p.e. on each end,
but it should be much lower in reality .
 We look for one type of SciFi that has:
Strong Light-Yield, Mechanically Strong, and High Detection Efficiency.
 Option 1 ---Square Fiber
 Option 2 ---Round Fiber
Charged Particle Direction
Good: Smaller Gaps (maximize the detection
efficiency), Easier Align&Assembling
Bad: Shorter Attenuation Length
Good: Longer Attenuation Length
Bad: Larger Gaps, Poor Trap-Efficiency (position
dependence)
For our SFT with 150 cm fibers, square fiber may be better.
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Prototype Test Project: SciFi Test
 SciFi Testing Setup:
The SciFi being testing:
 New Fiber-Samples from Kuraray:
1, x2 SCSF-78MJ , 1mm, Round, 3meters, Multi-Clad
2, x2 SCSF-78MSJ , 1mm, Round, 3meters,
mechanics stronger, Single-Clad (30% less light yield)
3, x2 SCSF-78J, 1mm, Square , 3meters
4, x2 SCSF-78J, 1.5mm, Square , 3meters
 From Hall-D: x8 SCSF-78MJ 1mm, Round, 2 meters
Goal:
Measuring the Light-Yield and Attenuation
Length for different types of SciFi.
3um
2um 1um
SciFi Polishing Tools
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Prototype Test Project: SciFi Test
 SciFi Testing Setup:
1-inch PMT (Hall-C)
Scintillator (HallC)
Ru106 Radiation
Source
SciFi
We built a 200cm x 20cm Black-Box !
Mounting
Block
Thank you! Walter Kellner
@Hall-C Machine Shop!
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Prototype Test Project: SciFi Test
 SciFi Testing Setup: Quick check
1mm 78MSJ-Round
1mm 78MJ-Round
 Checked the signals with Oscilloscope;
 Will take data with DAQ this week;
~5 p.e.
~8 p.e.
 Hall-D has done many tests with 78MJ
which gives ~ 8 p.e.;
 ~20 p.e. would be a good number to get
high detection efficiency (add two fibers);
 The fibers are needed to be polished with
1mm 78J-Square
1.5 mm 78J-Sqaure
better tools (borrowing a polishingmachine from Hall-D).
~7 p.e.
~10 p.e.
 Hall-D’s experiences and test results can
be adopted!
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Prototype Test Project: SciFi Test
 Assembling & Mounting: Just a plan.
 Carl Zorn and Brian Kross, etc. in the Detector Group have given many
suggestions
 Will learn from Carlos Ayerbe who built the SFT for KAOS@Mainz:
http://wwwa1.kph.uni-mainz.de/A1/publications/doctor/ayerbe.pdf
 Mark Emamian from Duke is helping the Mounting Frame design.
The plan is divided into groups
Rohacell
Foam
Fibers
Aluminum
Frame
Rohacell Foam+Carbon Fiber Foil
Screw
Mounting Cookie on each end (Scheme Draw)
 Challenge for us– How to avoid the horizontal SciFis to bend down?
Optical Glue
Solution: Glue them on a plane with Rohacell foam+carbon fiber foils
Problem: Adding more dense materials (potential radiation background)
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Prototype Test Project: SiPM Test
SiPM Avalanche Photodiode (APD)
pixels working in Geiger-mode
 Photon Detectors:
1, SiPMs: Silicon Photon Multiplier
 Cheap ~$10 per SiPM+~$10 power supply+~$10 Pre-Amp;
 Large Gain  ~~ x106 ;
 Insensitive to magnet field
 Need a Pre-Amp Design  Hall-D has a very good design
 Gain is temperature-depended
One photon only fire one pixel (unless
cross-talk or dark-current)
 Relatively larger dark current;
 Radiation damage by the neutron background;
 Cross-Talk
Hamamatsu MPPC S12572-100P/50P
Used in
Hall-B &
Hall-D for
testing
Hamamatsu Multi-Pixels Photon Counter (MPPC)
We newly
purchased
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Prototype Test Project: SiPM Test
 Photon Detectors:
2, MaPMTs (possible candidate)
 More commonly used;
 Multi-channels outputs
 Much cleaner background;
 High radiation tolerance;
 Degraded performance in strong magnet field;
 Cross Talk
 Expensive;
 Our Duke group has a 64ch H8500 MaPMT for test
 We will borrow a 16ch MaPMT from SBS
From Carlos
Ayerbe’s thesis
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Fiber+SiPM Mounting Block
Prototype Test Project: SiPM Test
Thank you,
Walter Kellner!
 SiPM Test Setup:
High Precision Power Supply (Hall-D)
x2 Low Voltage Power Supplies (Hall-A&-D)
Black Box (from Simona Malace)
Sr90
Temperature Sensor
Fan
SiPMs with Pre-Amp (Hall-D)
SiPMs with Pre-Amp (Stepan@Hall-B)
Goal:
Understand the performance of the SiPM --- Gain, Noise Level,
Stability with Temperature, ADC & TDC spectra.
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Prototype Test Project: SiPM Test
 SiPM Test Setup: (Stepan’s SiPMs+Pre-Amp)
1 p.e.
2 p.e.
3 p.e.
3 p.e.
2 p.e.
1 p.e.
Hamamatsu
Measurements
(what we expect to see)
 Not yet seen pretty pattern from scope
 More to learn about SiPM
 Data taking with DAQ will be proceeded soon;
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Prototype Test Project: Read-Out System
 Read-Out System of >2400 Output Channels:
1, SiPM (or MaPMT) + FastBus ADC + TDC
Requires a large amount of NIM modules and long delay cables
2, SiPM (or MaPMT) + fADC
Need >20 fADC & VME64 which are rare and expensive
3, A “Cheaper” Solution  EASiROC for SiPM or MaROC for MaPMT
 Developed by OMEGA@IN2P3;
 Pre-Amp integrated with adjustable Low/High Gains;
 ADC outputs and TDC outputs;
 One “OR” logic output for triggering; One “SUM” analog output;
 ~$130 for each chip (or <$5 per channel);
 Need an additional readout board (“expensive”)
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OMEGA Test Board (USB readout)
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Prototype Test Project: Read-Out System
 Read-Out System of >2400 Output Channels:
EASIROC (or the new version called CITIROC)
32 ADC
Outputs
32ch Inputs with
adjustable High/Low
Gain
32 TDC
Outputs
Logic Output
SiTCP read-out board designed at KEK (TCP/Ethernet 1Gbps )
NIM-based Read-Out Board designed by I. Nakamura (KEK) for J-PAC
 A new MaROC3 with a read-out board
(USB port) has been purchased for
With EASIROC+SiPM or MaROC+MaPMT,
the SFT will be “portable”!
SoLID-EC test; We will study its
performance with SULI students’ help.
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Summary:
 SFT provides a great option to improve the PRad experiment and can be applied to many other projects.
 Prototype Testing Project is undergoing:
(1) It took a few months to prepare the setup due to very limited resources.
(2) Received and receiving many helps from colleagues in Hall-A/B/C/D, Detector Group, Duke Univ, etc.
(3) We have almost everything set up and will have some serious results very soon.
 Near Term goals (not working n full-time):
 Test and choose SciFi;
 Test SiPM and MaPMT
 Design and build the mounting structure
 Assembling the 1.2m x 1.2m SFT is challenging but practicable.
 Three options of the read-out systems are available.
 Highly appreciate your suggestions and helps, and welcome to join.
 I hope one day the full size SFT can be built!
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Acknowledgement:
I am grateful to receive many helps from:

Hall-A: Alexandre Camsonne, J-P Chen, Jack Segal, etc

Hall-B: Sergey Boyariov, Stepan Stepanyan, Youri Sharabian, etc.

Hall-C: Joe Beaufait, Mark Jones, Walter Kellner, Simona Malace, Brad Sawatzky, etc

Hall-D: Elton Smith, Yi Qiang, etc

Detector Group: Brian Kross, Wenze Xi, Carl Zorn, etc.

RadCon: Adam Hartberger

Many other colleagues and friends
Special Thanks are given to:
•
JSA User Board that give me the Postdoc Prize and offer me such a precious opportunity
•
Hard working Graduate Student: Chao Peng (Duke), Li Ye (Mississippi Statue)
•
Brad Sawatzky and Yi Qiang who lend me many instruments and help me to complete the setup
•
Prof. Haiyan Gao, Yi Qiang and Stepan Stepanyan who give me many advices to design and
carry out this project.
•
Prof. Donal Day, Prof. Haiyan Gao and Doug Higimbotham who provide the reference letters.
•
And the PRad collaboration & SoLID collaboration.
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Cost Estimation of the Full-Size SFT:
• Each Fiber: 1mm width ( round or square ) is $1 per meter.
for 1.2m x 1.2m, we need roughly 2400 1.5m-long fibers for each plane to cover the gaps.
for x-y two planes, 4800 fibers ~ $7.2 K
• Photo-Detector: SiPM module $10 for each channel quoted from Hamamatsu.
Amplifier used in Hall-D: $10 for each channels ( plus Design Fee $???)
~~$80K
Power Supply (~$10 for each channel)
For one-end read-out: 2400 channels x $30 per channel ($72K + engineer design of the Pre-Amp)
• Mounting Frame and Supporting Structure ($???)
• Connectors + Cables + Tools + Supplies ($???)
• ReadOut+DAQ:
From SiPM to raw data: Discriminators, FastBus ADC & TDC (40 cards for each) (or fADC )
OR: EASIROC --- $100 for 32 channels
+ Read-Out Board ( we need to borrow designs and make all by ourselves ~$1500 per board or cheaper)
Total Read-Out: ~$120K
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