Alignment Electronics
for the New Small Wheel



ATLAS Muon Week in Israel
Weizmann Institute, 05-JUN-14


Kevan Hashemi
Physics Department
Brandeis University
http://alignment.hep.brandeis.edu

Existing System

The ATLAS End-Cap Alignment System Uses roughly:

All powered, controlled, and read out with the Long-Wire Data Acquisition System (LWDAQ).

Same system used by: ALICE Geometric Monitoring System, ALICE Space Frame Monitor, LHCb Inner Tracker Alignment, HIE-ISOLDE Alignment, and CMS Technical Coordination.

Overall: The system works well enough.

Obsolete Image Sensor

Property KAC00401 ICX424AL TC255P
Manufacturer Eastman Kodak Sony Semiconductor Texas Instruments
Technology CMOS CCD CCD
Sensor Area 5.1 mm × 3.3 mm 5.8 mm × 4.8 mm 3.4 mm × 2.4 mm
Pixel Dimensions 6.7 μm × 6.7 μm 7.4 μm × 7.4 μm 10 μm × 10 μm
Fill Factor Estimate <80% Observe ≈100% Observe >90%
Uniformity of Dark Current 10% 1% 1%
Uniformity of Sensitivity 10% 1% 1%
Package Size 12.2 mm × 12.2 mm 12.2 mmm × 9.5 mm 10.0 mm × 10.0 mm
Control Interface Volatile Configuration Bits Clock Voltages Clock Voltages
Output Format Serial Digital Pixel Voltages Pixel Voltages
Price ≈$40 $40 ≈$40
Table: Comparison of Image Sensors.

Importance of Fill Factor


Figure: BCAM Images At Various Ranges. Source is 650-nm laser diode. Sensor is TC255.

Linearity of ICX424AL BCAM


Figure: ICX424AL BCAM Non-Linearity Across Entire Field of View. Pixels 7.4 μm square. Residuals in microns on sensor plotted versus stage position. Image sharply-focused. Two red lasers at 3.1 m on 300-mm stage, camera focal range 3 m, lens focal length 48 mm, camera V0359. Repeat with poorly-focused spot residuals remain 0.2 μm rms.

Changes Required by ICX424

Challenges of New Small Wheel

We solve both the radiation resistance and density problems for light sources by switching to fiber-optic light sources rather than laser diode light sources.

We solve the radiation problem for our cameras by study and adaptation.

Fiber-Optic Light Sources


Figure: Contact Injection into Optical Fiber. Fiber diameter 125 μm.

Buck Regulator for LED Power


Breadboard Buck Regulator


Figure: Breadboard Buck Regulator

Importance of Radiation Spectra


Figure: Energy Absorption Coefficient for Air and Silicon. Data from NIST.

Specrum of ATLAS Background


Figure: Simulated Spectra of Photons and Neutrons at Inner Edge of nSW. Bin for <=1keV contains 40,000 thermal neutrons.

Spectrum of ATLAS Background Dose Rate


Figure: Simulated Dose Rate Spectrum for Photons and Neutrons at Inner Edge of nSW.

Irradiation with X-Rays

We are using x-rays to deliver slow ionizing doses.

We confirmed out dose calibration with a cesium-137 source of 500-keV γ.

Performance of Prototype ICX424AL Camera


Figure: ICX424AL Image after 450 Gy. Circle marks tungston sphere absorber.

Expected ATLAS Doses


Figure: Expected Dose Rate versus Radius in nSW. Assume 5×1034 1/cm2s and 14 TeV.

Neutron Tests

Single Event Upset Tets

Conclusion

Appendix: Linearity with Quadruple-Pixel Readout


Figure: ICX424 BCAM Non-Linearity Across Entire Field of View with Quadruple-Pixel Readout. Pixels 14.8 μm square. Residuals in microns on the image sensor plotted versus stage position. Image sharply-focused. Two red lasers at 3.1 m on 300-mm stage, lens focal length 48 mm, camera V0359. Repeat with poorly-focused spot residuals remain 0.2 μm rms.

Appendix: Dose Map from Background Group


Figure: Simulated Total Annual Ionizing Dose, Gy/yr. Luminosity 1034 1/cm2s, energy 14 TeV, 107 s running per year, 2012 detector geometry.