The UNH SVT Testing Facility: Status and Progress Sarah K. Phillips The University of New Hampshire May 28, 2013 UNH DOE Review

Silicon Microstrip Detectors Silicon microstrip detectors are used to detect particles that pass through them and are used in Particle physics experiments at accelerators Instruments on satellites Have good properties for particle physics: Excellent spatial resolution Good energy resolution Can cope with high rates Compact Are often used in tracking applications!

CLAS12 and the JLab Upgrade Jefferson Lab shut down in May 2012 to do a major upgrade. The accelerator will be upgraded to 12 GeV (from 6 GeV) A new experimental hall (Hall D) will be built The other three experimental halls will also receive beam energies up to 11 GeV To take advantage of the new energy range, Hall B will upgrade to a new detector system called CLAS12. Among the new detector systems being developed is a silicon vertex tracker (SVT) Close to the target; will provide excellent position resolution for vertex determination in reactions. The UNH Nuclear Group is part of the development of these detectors.

CLAS12 and the Jefferson Lab Upgrade

CLAS12 and the Jefferson Lab Upgrade

Silicon Vertex Tracker Silicon strips in alternating layers are placed at different angles to provide stereo readout Layers provide three spatial points for a particle track, allowing for momentum determination by measuring the curvature of the track in the magnetic field of the solenoid. Barrel-like layers around the target φ-coverage ~2π θ-coverage ~ 35° - 125° Momentum resolution ~50 MeV/c φ-resolution ~5 mrad θ-resolution ~20 mrad Tracking Efficiency > 90%

Silicon Vertex Tracker Each detector is made of: Three sensors Front-end electronics Support structure Our detectors are being assembled at Fermilab.

Silicon Vertex Tracker Sensors: single-sided, 320 µm silicon Cross-sectional view showing the different layers of the spacing of the strip Strip width ~ 8 μm and implant depth 1.3 μm Readout pitch ~150 μm provides a spatial resolution of ~ 50 μm in r and Φ Hamamatsu Corporation is making our silicon strip sensors (have experience with CMS and ATLAS)

Laser Testing of Silicon Detectors It is important to perform quality assurance tests and evaluate the performance of the detectors before their installation in the full detector system for CLAS12! Need to know: Quality control of the individual detector assemblies Verify that the fundamental detector properties of the intended design are met. Laser beams are used to test silicon detectors, since the laser light simulates the signals generated by charged particles in a silicon detector

Laser Testing of Silicon Detectors Concept: A precision position mechanism scans infrared laser light across the detector. The data are read out and analyzed for properties such as basic quality assurance, strip-to-strip variations, attenuation along the detector, charge sharing among adjacent readout strips, position resolution, timing resolution, high voltage scans, etc. The UNH laser testing facility is based on designs used for experiments at Fermilab, Brookhaven, and CERN. For example: Y. Tomita, M. Nakamura, and K. Niwa, Nucl. Instrum. Meth. A 270, 403 (1988) S. Shaheen et al., Nucl. Instrum. Meth. A 352, 573 (1995) T. Akimoto et al., Nucl. Instrum. Meth. A 556, 459 (2006)

Laser Testing Facility Design Fiber Optic Cable Dark Box/Laser Enclosure Power Supply DAQ and Rail Control Computer Optics Precision Rails Detector Lower-Precision Rail

Major Equipment for Facility Silicon microstrip detectors require careful handling and clean, dry storage. Cleanroom Dry storage system Dark box / laser enclosure Laser and optics Precision rail system for scanning DAQ system

Cleanroom Silicon detectors are delicate! Susceptible to dust and humidity Require a cleanroom environment Have special dry storage requirements Made by Pacific Environmental Technologies, Inc. Softwall clean room, ISO 7/Class 10,000 12' W x 14' L with an internal 4'x8' gowning room

Building the Cleanroom

Major Equipment Dry Storage System Dry nitrogen purge system 19.7 cu. ft. chest freezer by GE (inner dimensions: 55.25” w x 23.5” d x 26.22” h) Teflon 1/4” tubing, single stage brass regulator, compression fittings Viton o-rings, Dow Corning 739 sealant to seal fittings; PTFE pipe sealing tape to seal the threading. Flow: plan to run at about 0.48 cubic ft. per hour once we are in production mode; have a max flow rate of 2 cubic ft. per hour.

Major Equipment Dark Enclosure DAQ System Bosch-Rexroth extruded aluminum and aluminum sheeting panels (1/16th thickness); door made from 39” x 39” x 1/8” aluminum plate attached with a piano hinge. Internal dimensions: 2 m x 1 m x 1 m (outer dimensions about 80 mm larger to account for width of the frame) Black Poron foam in aluminum angle to ensure light-tightness. DAQ System Dell Workstation 9200 C++ code written by UNH students and JLab staff Data analysis done using ROOT

Major Equipment Laser System Optics Berkeley Nucleonics Corporation Model 106C 2mW Max power: 1 mW Spectral peak: 1064 nm, Spectral width: 5 nm Transition times (10% to 90%): 1 ns rise time, 2 ns fall time dynamic range: 13 dB pulse width: internal 3 ns to 640 s FC connectors Optics New Focusing package by OZ Optics (should be able to achieve ~10 m laser spot size).

Major Equipment Rail system Two sections, made by Newmark Systems, Inc. Precision rails to scan light precisely over sensor A coarse rail the detector rides on to move to the next sensor in the stave. Precision rails: three axis length: x=200 mm, y=200 mm, z=50 mm resolution: 0.1 m accuracy: 5 m repeatability:  0.5 m max speed = 50 mm/sec Coarse rail: one rail 16 in. travel resolution: 0.13 microns accuracy: 0.0006 mm/mm

Laser Test Stand Precision rail system inside laser enclosure (mounted on optics table)

First Measurements We have been developing our measurements using a surplus CMS detector from Fermilab (pitch 73 μm). Measurements: Noise measurements Gain measurements Position scans of the strips Charge sharing between the strips

Noise Measurements Procedure: Inject a known signal from the waveform generator into specific channels Increase minimum threshold until signal falls to zero Fit with Gaussian and extract equivalent noise charge (ENC)

Gain Measurements Procedure: Inject a known signals at varying amplitudes from the waveform generator into specific channels Fit data with linear fit and extract gain from the slope

Charge Sharing Measurements The charge shared across adjacent strips can be described by the function: η 𝑥 0 = 𝑃𝐻 𝑅 𝑥 0 𝑃𝐻 𝐿 𝑥 0 + 𝑃𝐻 𝑅 𝑥 0 PH denotes the pulse height across the left and right strips.

Future Plans All major equipment going Working on focusing techniques to achieve optimal laser beam spot with the new focusing package Continue developing the charge sharing measurements and refining measurements to be more automated Calibration measurements planned with a radioactive source Test the first article detectors for JLab in fall 2013 – winter 2014 Test the production detectors for JLab (winer 2014 – spring 2014)

Conclusions Lasers are a powerful tool in testing silicon detectors for nuclear and high-energy particle physics experiments. The laser testing facility at UNH will test the silicon detectors for JLab's CLAS12. Can be used with silicon sensors for other projects, so will have an extended career. Great project for undergraduates to get hands-on research experience and make connections at a national lab.

Backup Slides

Silicon Vertex Tracker Sensors: single-sided, 320 µm silicon Cross-sectional view showing the different layers of the spacing of the strip Strip width ~ 8 μm and implant depth 1.3 μm Readout pitch ~150 μm provides a spatial resolution of ~ 50 μm in r and Φ Hamamatsu Corporation is making our silicon strip sensors (have experience with CMS and ATLAS)