IBIC2023

Development of a Precise 4d Emittance Meter
Using Differential Slit Image Processing

Bokkyun (BK) Shin1, Chang-kyu Sung1, Garam Hahn1, Moses Chung2
1Pohang Accelerator Laboratory, Korea

2Ulsan National Institute of Science and Technology, Korea

IBIC2023, Saskatoon, Canada

Sep. 13, 2023

Introduction

4D emittance & Differential Slit method
x-y coupling beam: 4D phase space (x-x', x-y', y-x', y-y')
PLS-IINewMethod•Dual Slit method, Pepper pot

Virtual Pepper Pot method- image processing slit position x and y slit image => 1D scan → 2D ScanG. Z. Georgiev and M. Krasilnikov, IBIC 19'OneMoreStep•Uncertainty from Slit width → Differential slit method• Differential Slit method:- Using Slit position x and x+slit width slit image→ narrower than slit moving step size → precise measurement

2We introduce our differencial slit method with simulation data analysis

bkshin@postech.ac.kr PAL

IBIC 2023

Introduction

Slit Design
Target Beam Line: PAL-eLABs (or ITF) Ebeam =70 MeV, Korea 4GSR LINAC Ebeam =200 MeV

Cover 15 mmsize beamPunchingby etching

50 μm Stainless steel- etching Manufacturing- BKG by beam scatteringbkshin@postech.ac.kr PAL

IBIC 2023

3

Simulation

Simulation• Beam Condition: PAL-eLABs (or ITF)

• 70 MeV, 10~20 nm ⋅ rad w/ artificially rotate• Slit-Screen Dist.: 3.5 m• Slit moving every 20 μm ⇒ 10 Hz with 200 μm/s

Geant4: beam interaction

openCV: Image processing- 50 μm thickness Slit

- Edep → px count- 100 μm thickness YAG- px res: 20 μm x 20 μx→ Edep in YAG Screen- resol.: 1000 x1000- 12 Bit imageBackground Beam Scattering by 50μm
Stainless plate is negligible→ 16 bit scaled movie format
bkshin@postech.ac.kr PAL

IBIC 2023

4

Analysis"Differential Slit Method" (This Topic)
Screeen by Position 1

Slit

Differential Slit image

Slit Position 1

Screeen by Position 2

Minimum px count pick up

Equivalent 2.1 μm slit

Slit Position 2
10 frames after position 1
bkshin@postech.ac.kr PAL

IBIC 2023

6

Analysis

Analysis: Virtual Pepper Pot
Differential Slit
Position 1

Result VPP Image

Differential Slit
Position 1

Differential Slit
Position 2bkshin@postech.ac.kr PAL

IBIC 2023

Minimum px count pick up

Differential Slit
Position 27

Resultw/ w/o Differential Slit

w/ow/Input α 4.467 β 4.390 ε 7.449 nm radbkshin@postech.ac.kr PAL

α 3.853
β 4.530
ε 7.650 nm⋅rad

α 3.145
β 3.884
ε 9.530 nm⋅radIBIC 2023

Input α -2.257 β 14.775 ε : 3.977E-03

α: -2.002
β: 13.064
ε: 3.829 nm⋅rad

α: -0.748
β: 6.005
ε: 9.390 nm⋅rad8

Analysis

4D Emittance ResultINPUTRECON.

INPUT

4.467 3.871
αβ4.390 4.549
ε (nm rad) 7.449 7.650

α-0.379 -0.365
β1.377 1.657
ε (nm rad) 23.73 21.24

3%

INPUT

11%RECON.

INPUT

α-0.479 -0.468
β0.826 1.004
ε (nm rad) 23.87 22.16

RECON.

α1.914 1.821
β2.161 2.496
ε (nm rad) 9.137 8.932

7%bkshin@postech.ac.kr PAL

RECON.

2%

IBIC 2023

9Analysis

Comparison

VPP

Position X

Min(Position Y,

Differential
Slit

Position XMin

bkshin@postech.ac.kr PAL

Position X+Slit Width,(IBIC 2023)=)=10

Summary

Experiment Plan & Summary3.5 m

PAL-eLABs Lattice

by End of this Year
Beam Rotation
Bucking coil

Skew QuadSummary• Differential Slit: solve Slit width uncertainty with simple technique⇒ Apply all slit-screen method⇒ VPP with Differencial Slit: precise 4D emittance analyzer
bkshin@postech.ac.kr PAL

IBIC 202311