1. 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

2. Contents Introduction Diamond Detector Characteristics
Diamond Detector PHIL
Design for In Vacuum Diamond Detector
Summary and Future Plan

3. Introduction Motivations: Goals of ATF ATF2
Accelerator Testing Facility (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)

4. Beam Halo Measurement Using
Wire Scanners

5. Diamond Detector Characteristics

6. 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)

7. 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

8. 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

9. Diamond Detector Test @ PHIL
(In Air)

10. 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;

11. Signal Form for Different Beam Charge
Without box and with 24dB attenuator and 2mm collimator, distance to exit is ≈4.5cm
Expected
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

12. 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

13. Design for In Vacuum Diamond Detector

14. 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.

15. Mechanical Design %

16. 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

17. 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 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.

18. Thank you for your attention !

19. Backup Slides

20. 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

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