Investigation of Beam Halo at ATF2

Shan Liu, Philip Bambade, Sha Bai, Dou Wang, Illia Khvastunov

ECFA, Hamburg, 29 May, 2013

2

Contents

• Introduction

• General Study of Beam Halo

• Beam Halo Measurement and Collimation

• Diamond Detector R&D

• Diamond Detector Test @ PHIL

• Summary and Future Plan

Diamond Sensor

Shintake Monitor

Introduction

3

Compton

ATF2

Motivations: Beam halo transverse distribution unknown → investigate halo model Probe Compton recoiled electron→ investigate the higher order contributions to the Compton process (in the future)

General Study of Beam Halo

4

Theory Beam Halo Generation -> D. Wang, T. Demma

MAD-X Simulation -> Halo Collimation->@LAL & IFIC

GEANT4/BDSIM Simulation -> I. Khvastunov

Diamond Test @ PHIL

Halo measurement @ATF2

Simulation

Experiment

In air

In vacuum

Wire Scanners

Instrumentation Diamond Detector R &D

Diamond Detector

Beam Halo Measurement & Collimation

Beam Halo Measurement

Energy spread of halo = ? Unknown;

6

x-> the distance from the beam center as a unit of σ

Halo Density

T. Suehara et al., “Design of a Nanometer Beam Size Monitor for ATF2”, arXiv:0810.5467v1

• First beam halo measurements were done in 2005 using the wire scanners in the extraction line -> need to be updated for present beam optics;

• No energy halo measurement was performed before -> Energy spread of halo is unknown -> can be investigated with wire scanners by measuring halo distribution by changing the vertical dispersion in the diagnostic section.

Scintillation Detector

MW2XCherenkov Detector

Wire Scanners & Detectors

MW3X

MW2X

MW4XMW1X-(Post-IP)

Diamond Detector

2013 April Run @ ATF MW2X MW3X MW1X-(Post-IP) -> Initial data analysis

MW1X-Post IP Wire Scanner

Step 2： X & Y Scan to get Gaussian Peak and sigma

Step 1： Overall Scan to find wire position

Y X

9

Beam Distribution After Normalization 3to5sigma_600V 4to6sigma_1100V 5to7sigma_1200V 6to8sigma_1300V 7to10sigma_1500V 8to15sigma_1600V 10to30sigma_1600V -3to3sigma_500V -3to-5sigma_900V -4to-6sigma_1100V -5to-7sigma_1200V -6to-8sigma_1400V -7to-10sigma_1500V -8to-15sigma_1500V -10to-20sigma_1600V -15to-20sigma_1600V Gaussian fit to beam core

20 22 24 26 28 30 32

10

100

1000

ICT

Cor

rect

ed S

igna

l Str

engt

h

Wire Position (mm)

4 6 8 10 12 14 16

10

100

1000

Gaussian fit to beam core -3to-5sigma_900V -4to-6sigma_1100V -5to-7sigma_1200V -6to-8sigma_1400V -7to-10sigma_1500V -8to-15sigma_1500V -10to-20sigma_1600V -15to-20sigma_1600V -3to3sigma_500V 3to5sigma_600V 4to6sigma_1100V 5to7sigma_1100V 6to8sigma_1100V 7to10sigma_1200V 8to15sigma_1300V 10to20sigma_1400V 15to25sigma_1500VIC

T C

orre

cte

d S

ign

al S

tre

ngt

h

Wire Position (mm)

Vertical beam

Horizontal beam

Collimated by MREF3FF? -> to be verified

down sideup side

Halo+Pedestal+Background?

Mad-X Simulation Results for Beam & Halo & Compton Signal @ Sensor

Total Number (in simulation)

Total Number (in experiment)

Min.～ Max. Number/mm2 @

Sensor

Charge signal/mm2

Beam 105 1010 6163*105 1.6887*10-6C=1.6887μC

Halo(δp/p0=0.01)

105 107 114 *102 3.1236*10-11C=31.236pC

Halo(δp/p0=0.0008)

105 107 224*102 6.1376*10-11C=61.376pC

Compton 2834 28340 3*10～ 52 *10

82.2fC～ 1.4284pC 10

δp/p0=0.0008Beam HaloCompton

δp/p0=0.01

11

Halo Collimation

Energy & betatron collimation needed

Vertical Halo Hit BDUMP → may re-generate halo of off-momentum beam particles;

Horizontal HaloMay cover the Compton signal especially in case of large initial energy spread.

Betatron collimationneeded

Preliminary

HaloCompton

δp/p0=0.01

QF1X

QF6X

x

P

/Dmyvar

D

x

pp

，

Add collimatorsR=0.003m

Possible to probe Compton

R=0.016m

QF6X

Diamond Detector R&D

Diamond Detector Characteristics

13

PHIL ATF2

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 elocity (μm ns-1)Dielectric constant Neutron transmutation cross-section(mb)Energy per e-h pair (eV)Atomic numberAv.min.ionizing signal per 100 μm (e)

3.55.5>1012

107

180012002205.6

3.21363600

2.321.1105

103

150050010011.7

803.6148000

• Large band-gap low leakage current⇒• High breakdown field• High mobility fast charge collection⇒• Large thermal conductivity• High binding energy Radiation hardness⇒ Fast pulse < 1 ns⇒

ADVANTAGES

Energy loss of an electron in diamond & silicon

Diamond Detector Characteristics

Configurations: - Pads : mm2 x 500 m - Strips & pixels - Membranes ( 5 m) - Orthogonal/ Parallel orientation Types: - Poly crystalline diamond - Single crystalline diamond

Diamond detectors

Dark Current Measurement

14

Charge created by 1MIP in diamond → 2.74 fC

Metallised with Al or Ti/Pt/Au(100nm)

Surface: 4.5X4.5mm2

15

Detector Holder Design

Under design by Frederic Bogard

Vacuum Chamber

Moveable Stage

Horizontal Scan

Vertical Scan

Diamond Detector

CeramicBase

Diamond Detector Test @ PHIL

17

Diamond Detector Test @ PHIL

In-vacuum single crystal CVD diamond sensor profile scanner -> for PHIL diagnostic

Test of fast remote readout (fast heliax coax cable + ASIC) with particles at end of beam line, using existing single crystal 4.5x4.5mm CVD diamond pad sensor

PHIL Electron Beam Parameters(given by Hugues Monard)

Charge: 10 pC-250 pC/bunch

(1 bunch per RF pulse) ;

Duration of Charge: 7 ps

FWHM;

Charge Stablility: < 2%;

Maximum Energy: 5 MeV;

Minimum Dispersion: < 1%;

Beam Size -> ?

18

First Test @ PHIL

50 m RG58 coax cable

ExperimentalSetup

Diamond Sensor

Electron Beam

Camera

Performed on 08.02.2013

19

First Test Results @ PHILFilter Total

ChargeAmplitude@sensor

100% 180pC 65V

62% 130 pC 55V

31% 95pC 45V

3% 14pC 7V

0.1% ≈0.1pC? 40mV0 50 100 150 200 250 300 350 400 450 500

0

10

20

30

40

50

60

70

Amplitude @ sensor VS Bias voltage

Minimum signalNumber of electronsAttenuation of cablesCharge collection efficiency Calibration

20

Second Test @ PHIL

20dB AttenuatorYAG screen

8cm

10 cm

Dark Current

Beam Energy : 3 MeV; Beam Size: σ ≈ 4.5 cmBeam Charge: 33 pC (measured at ICT 1, obtained using a 10% filter on the laser)

Perf

orm

ed o

n 20

.03.

2013

Summary• We can investigate halo propagating model by measuring the beam halo using

diamond sensor; • We probably need to cut the beam halo signal to probe the Compton

spectrum. Betatron collimation may be needed for both horizontal and vertical planes as well as energy collimation for horizontal plane (collaboration with IFIC);

• First tests of diamond sensor @ PHIL;• First measurements of halo at ATF2.

Future Plans Continue data analysis for the ATF2 halo measurement using wire scanners; Energy halo measurement using wire scanners at ATF2 in June (by S. Bai); Investigation of halo generation theory (by D. Wang and T. Demma); BDSIM-GEANT4 simulation for beam halo regeneration study (by I. Khvatunov) Calibrate the readout of diamond sensor using Sr source in June; Finish the design of in vacuum detector and detector holder, install and test in

air @ PHIL before December; → Install the diamond sensor @ ATF2 in 2014

21

Thank you for your attention !

Backup Slides

24

Beam Distribution Before Normalization

3to5sigma_600V 4to6sigma_1100V 5to7sigma_1200V 6to8sigma_1300V 7to10sigma_1500V 8to15sigma_1600V 10to30sigma_1600V -3to3sigma_500V -3to-5sigma_900V -4to-6sigma_1100V -5to-7sigma_1200V -6to-8sigma_1400V -7to-10sigma_1500V -8to-15sigma_1500V -10to-20sigma_1600V -15to-20sigma_1600V

18 19 20 21 22 23 24 25 26 27 28 29

1000

10000

ICT

Co

rre

cte

d S

ign

al S

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ng

th

Wire Position (mm)

START

MMQM14FF

MMQM12FF

MMQD10AFF

MMQF9AFF

MMQD6FF

MMQF5AFF

MMQD4AFF

MMQD2AFF

MMPIP

MMDUMP0.50.60.70.80.9

11.11.2

Ratio of halo (60 sigma) loss on Y axis

BX10BY1_glenBX10BY1BX10BY2BX10BY4BX10BY6BX10BY8BX10BY10

Change the beta_y*

START

MMQM15FF

MMFB2FF

MMQM12FF

MMQD10BFF

MMQF9BFF

MMQF9AFF

MMQF7FF

MMQF5BFF

MMQF5AFF

MMSD4FF

MMQF3FF

MMQD2AFF IP

MBDUMPa

MMDUMP0.5

0.6

0.7

0.8

0.9

1

1.1Ratio of halo (100 sigma) loss on Y axis

BX10BY1_glenBX10BY1BX10BY2BX10BY4BX10BY6BX10BY8BX10BY10

START

MMQM15FF

MMFB2FF

MMQM12FF

MMQD10BFF

MMQF9BFF

MMQF9AFF

MMQF7FF

MMQF5BFF

MMQF5AFF

MMSD4FF

MMQF3FF

MMQD2AFF IP

MBDUMPa

MMDUMP0.75

0.8

0.85

0.9

0.95

1

1.05

Ratio of halo (40 sigma) loss on Y axis

BX10BY1

BX10BY2

BX10BY4

BX10BY6

BX10BY8

BX10BY10

25

Almost no halo loss at BDUMP for BX10BY10

Larger beta_y* can reduce vertical halo hitting BDUMP

beam pipe

Vertical Collimation at QD10

START

MM

QM15FF

MM

FB2FF

MM

QM12FF

MM

QD10BFF

MM

QF9BFF

MM

QF9AFF

MM

QF7FF

MM

QF5BFF

MM

QF5AFF

MM

SD4FF

MM

QF3FF

MM

QD2AFF IP

MBDUM

Pa

MM

DUMP

0

0.2

0.4

0.6

0.8

1

1.2

Ratio of halo (40sigma) loss on Y axis with deltap_0.0008

Aper_0.010_YAper_0.008_YAper_0.006_YAper_0.005_Y

START

MM

QM15FF

MM

FB2FF

MM

QM12FF

MM

QD10BFF

MM

QF9BFF

MM

QF9AFF

MM

QF7FF

MM

QF5BFF

MM

QF5AFF

MM

SD4FF

MM

QF3FF

MM

QD2AFF IP

MBDUM

Pa

MM

DUMP

00.20.40.60.8

11.2

Ratio of halo (40sigma) loss on Y axis with deltap_0.01

Aper_0.010_Y

Aper_0.008_Y

Aper_0.006_Y

Aper_0.005_Y

Initial Aperture Size:

R=0.01m

26

No halo loss at BDUMP

Vertical Beam Size @ QD10:

σy =0.3336mm

15σ y

Horizontal Collimation at QF1X

27

R=0.003m

Compton still covered by halo

Energy Spread:

Flat deltap= 0.01

Initial Aperture Size: R=0.016m

Horizontal Collimation at QF6X

R=0.006m R=0.003m

28

Possible to probe Compton

Energy Spread:

Flat deltap= 0.01

Initial Aperture Size:R=0.016m