Status of Forward Calorimetry R&D: Report from the FCAL Collaboration

1. Americas Workshop on Linear Colliders Fermi National Accelerator Laboratory May 12-16, 2014 Status of Forward Calorimetry R&D: Report from the FCAL Collaboration Bruce A. Schumm Santa Cruz Institute for Particle Physics University of California, Santa Cruz

2. Example Very Forward Region of the ILD and a CLIC Detector • Optimisation of the design of the very forward region of LC detector • Precision luminosity measurement • Fast feedback and beam tuning • Detector hermeticity • Challenge: Fast readout (Wolfgang Lohmann) Detector Workshop Terascale

3. Luminosity Measurement • Precise measurement of the luminosity • (10-3 at ILC, 10-2 at CLIC) • Low angle physics • New challenge: Beamstrahlung Gauge process for the luminosity measurement: Bhabha scattering e+e-e+e- (g) L= N / s Count Bhabha events From theory (Wolfgang Lohmann) Detector Workshop Terascale

4. Beam Tuning and electron tagging BeamCal (+Pair Monitor) • Fast luminosity estimate using beamstrahlung (bunch-by-bunch at ILC) • Beam parameter estimation • Fast feedback to the machine • Low angle electron tagging Beam parameter determination and fast feed-back Bunch-by-bunch at ILC Detector Workshop Terascale (Wolfgang Lohmann)

5. FCAL Collaboration Goals and Activities • FCAL aims to generate complete designs of both forward detection elements (LumiCal, BeamCal) • Challenges include: Alignment and precision, data throughput, radiation hardness • Current activities include • Sensor development • Prototypes for full beam testing • Application-specific electronics development • Alignment systems • Radiation damage studies • Simulation for instrumentation design and physics studies (not discussed here) AWLC-14 Fermilab

6. Sensors Development Characterisation of a GaAs sensor on the probe-station Silicon sensor prototype for LumiCal p on n, strip pitch 1.8 mm 40 sensorsavailable Institutes: IFJ PAN Cracow, DESY, Tel Aviv (TAU) Electrical characterization done, matches quality criteria Compensated GaAs Institutes: Tomsk, DESY-JINR collaboration (BMBF supported) Electrical characterization at JINR and DESY, 30 sensors of sufficient quality (Wolfgang Lohmann) Detector Workshop Terascale

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8. Beam-test Results Scan across a pad boundary BeamCal sensor Wolfgang Lohmann LumiCal sensor Detector Workshop Terascale

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11. Testbeam Prototype Structure Status and PLans OleksandrBorysov AWLC-14 Fermilab

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14. Radiation Damage Studies Marek Idzik AWLC-14 Fermilab

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17. Dedicated BeamCal Readout • 180 nm TSMC technology • 10 bit SAR ADC • 4 channel version in summer 2014 • Assembled sensor planes for beam tests after 2015 Wolfgang Lohmann Detector Workshop Terascale

18. Mechanical aspects of LumiCal alignment LeszekZawiejski

19. The design of the LAS system The alignmen system may include two components: ● IR laser + PSD system: infra-red laser beam and semi-transparent position sensitive detectors ● FSI system: tunable laser(s), beam splitters, isolator, Fabry-Perot interferometer, retroreflectors, fibers, collimators, photodetectors, lens FSI - Frequency Scanned Interferometry): The absolute distance measurements between LumiCal’s IR Laser + PSD LeszekZawiejski

20. Position Sensitive Detectors Laser beam position measurements Light transmission: above 85% for  > 780 nm Fluctuations increasing with distance along the laser beam. They can be related to: laser instability with an increase of beam diameter and noise of the sensor. Data from laser working since hours show smaller fluctuations An example: beam profile signals from the X-strips along the moving beam. The available aperture for laser beam is 5 x 5 mm2 for sensor. The mean positions mxi were obtained from a Gaussian fit to observed signals LeszekZawiejski

21. Summary LeszekZawiejski ●The accuracy received in preliminary measurements of the beam position was less than 20 micrometers, using the layout of 6 semi-transparentsensors. Animprovement of the conditions of measurement (like thermal insulation)will lead to a smaller value. ● For beam test measurements and further development of the prototype a new complete system (PSD with readout and DAQ) seems to be necessary. Question is if this will be possible? Another option which can provide the measurement of transverse displacements is optical system RASNIK (Red Alignment System NIKHEF) ● FSI elements which recently were collected allow to build a simple prototype. The FSI studies will be continued after finished some tests performed by the producer for tunable laser. ● Several steps are planned during such studies, leading towards the final prototype. This will be continued inside the AIDA2 project.

22. Radiation Damage Studies SLAC Experiment T506: Electromagnetically-Induced Radiation Damage to Solid State Sensors Tungsten radiators Sensor Beam Beam AWLC-14 Fermilab

23. Example Radiation Damage Result • N-type bulk • Magnetic Czochralski • Exposures up to 220 mrad • Including (accidental) annealing • Further T506 goals: • Explore different Si sensor technologies (p-type, float-zone • Explore GaAs sensors • Higher doses AWLC-14 Fermilab

24. Summary and Conclusions Large, international group collaborating well towards development of forward calorimetry Good progress towards prototype BeamCal and LumiCal systems Challenging questions of alignment (prototype mechanical stack, alignment system development) and data rate (electronics development) being met In good shape for potential drive to build detectors for a realized Linear Collider AWLC-14 Fermilab

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