FCPPL, Clermont-Ferrand , 8-10 April, 2014 Diamond sensor development for beam halo and Compton process measurements at ATF2 S. Liu, P. Bambade, S. Bai, F. Bogard, J-N Cayla, N. Fuster Martinez, I. Khvastunov, H.Monard, C. Sylvia, T. Tauchi, N. Terunuma, T. Vinatier, D. Wang FCPPL, Clermont-Ferrand , 8-10 April, 2014

Contents Introduction Diamond Detector Characteristics Diamond Detector Test @ PHIL Design for In Vacuum Diamond Detector Summary and Future Plan

Introduction Motivations: Goals of ATF ATF2 Accelerator Testing Facility (ATF) @KEK (Japan) : low energy (1.3GeV) prototype of the final focus system for ILC and CLIC ATF2 64.4nm beam size measured in Mar. 2013 Shintake Monitor Diamond Sensor Compton Motivations: Beam halo transverse distribution unknown → investigate halo model Goals of ATF goal 1—achieving the 37 nm design vertical beam size at the IP; goal 2—stabilizing the beam at that point at the nanometer level; Probe Compton recoiled electron→ investigate the higher order contributions to the Compton process (in the future)

Beam Halo Measurement Using Wire Scanners

Diamond Detector Characteristics

Diamond Detector Characteristics Property Diamond Silicon Density (g m-3) Band gap (eV) Resistivity (Ω cm) Breakdown voltage (V cm -1) Electron mobility (cm3 V-1 s-1) Hole mobility (cm3 V-1 s-1) Saturation velocity (μm ns-1) Dielectric constant Neutron transmutation cross-section(mb) Energy per e-h pair (eV) Atomic number Av.min.ionizing signal per 100 μm (e) 3.5 5.5 >1012 107 1900 2300 141 (e-) 96(hole) 5.6 3.2 13 6 3600 2.32 1.1 105 103 1500 500 100 11.7 80 3.6 14 8000 ADVANTAGES • Large band-gap⇒ low leakage current • High breakdown field • High mobility⇒ fast charge collection • Large thermal conductivity • High binding energy⇒ Radiation hardness Fast pulse ⇒ several ns Leakage Current Measurement Surface: 4.5X4.5mm2 Thickness: 500um Capacitance: ≈2pC Metallized with Al or Ti/Pt/Au(100nm)

Diamond Detector Characteristics High voltage side readout GEOMETRIES Diamond detectors: - Pads : mm2 x 500 m - Strips & pixels - Membranes ( 5 m) Diamond type: - Poly crystalline diamond - Single crystalline diamond Low voltage side readout

Diamond Detector Signal FWHM ≈4ns With 40dB amplifier 2.27 MeV 0.55 MeV 241Am alpha source: Eα = 5.4 MeV Expected charge from 1MIP: Q = 2.74 fC Minimum charge detected: Q ≈ 11 fC (without external trigger) timebase changed for bias voltage<200V +10V to +150V +200V to +400V Hole -200V to -400V Electrons Preliminary result Charge collect efficiency

Diamond Detector Test @ PHIL (In Air)

Diamond Detector Test @ PHIL Test of fast remote readout (amplifier or attenuator +fast heliax coax cable ) with particles at end of beam line, using existing single crystal 4.5x4.5mm CVD diamond pad sensor -> check the linearity of output signal Camera Diamond Sensor Lanex screen: > 30fC PHIL Electron Beam Parameters Charge: 1pC-500 pC/bunch (1 bunch per RF pulse) ; Duration of Charge: 7 ps FWHM; Charge Stablility: < 2%; Beam Energy: 3 to 5MeV;

Signal Form for Different Beam Charge Without box and with 24dB attenuator and 2mm collimator, distance to exit is ≈4.5cm Expected Signal @ATF2 Total # Min. ～Max. #/mm2 @ Sensor Charge collected/mm2 Beam 1010 6.16*107 1.6887μC Halo (δp/p0=0.01) 107 1.14 *104 31.236pC Halo (δp/p0=0.0008) 2.24*104 61.376pC Compton 28340 3*10～5.2*102 82.2fC～1.4284pC time, s Signal strength, V 𝑉 𝑑 = 𝑉 𝑏 ∗ 1 1+ 𝑘 𝑄∗𝑅 𝑉 𝑑 = 𝑄∗𝑅 𝑡 𝑡= 𝑘 𝑉 𝑏 − 𝑉 𝑑 With 107 e- Voltage drop: Vd = 247V ↔ Bias voltage: Vb= 400V

Experiment Results Preliminary result Preliminary result Expected line for output charge Preliminary result Collected charge in the range 105 to 106 e- well fitted the expected value -> camera sensitivity need to be improved for lower range charge measurement 105 to 106 e- Data taken on 04.Apr.14 Preliminary result Collected charge start to get saturated due to recombination in the range >106 e- 106 to 108 e- Data taken on 12.Mar.14

Design for In Vacuum Diamond Detector

PHIL ATF2 Diamond Detector Same "plug compatible" design for PHIL and ATF2: fabrication will be completed in April 2014 before testing in May-June at PHIL.

Mechanical Design %

Parameters for circuit set based on Design of Electronics PCB Diamond Special channel for big signal (beam core) Top side of diamond Parameters for circuit set based on CH2 with R3=0.51Ω Cutoff frequency for HV Reserved Charge Charging time constant Bottom side of diamond 50kOhm 50kOhm

Summary and Future Plan We can investigate halo propagating model by measuring the beam halo using diamond detector; Using diamond detector we have successfully detected a minimum signal of several electrons by using 40dB amplifier and a maximum signal of 108 electrons by using 24dB attenuator; Diamond detector tests @ PHIL were done for the range from 105 to 108 particles with measurable input charge -> linear response up to 105 is expected, signal broadening and saturation in the high intensity regime to be interpreted quantitatively; Parallel tests using 90Sr (e-) and 241Am (α) sources to characterize the diamond detector are carried out in the clean room, cosmic muon test was also done and to be analysed ; Tests with diamond detector in air will continue before the installation for new setup in vacuum. The design for diamond detector for vacuum is done, fabrication will be completed in April 2014 before testing in May-June at PHIL and installation at ATF2 in autumn.

Thank you for your attention !

Backup Slides

Experiment Results Preliminary result Data taken on 12.Mar.14 Calibration of Lanex with ICT2 before collimator Data taken on 04.Apr.14 Expected line for output charge Preliminary result Calibration of Lanex with Faraday cup after collimator

Noise Analysis CIVIDEC 40dB amplifier MITEQ 20dB+20dB amplifier