Experiments on deflection of charged Experiments on deflection of - PowerPoint PPT Presentation

Experiments on deflection of charged Experiments on deflection of charged Experiments on deflection of charged Experiments on deflection of charged particles in Japan for ILC and J particles in Japan for ILC and J- -PARC. PARC. S. Strokov Hiroshima University

Collaborators Collaborators V. Biryukov, Yu. Chesnokov Institute for High Energy Physics Russia Institute for High Energy Physics, Russia S. Sawada KEK – High Energy Accelerator Research Organization T. Takahashi, I. Endo, M. Iinuma, H. Sato, K. Ueda Graduate School of Advanced Sciences of Matter, Hi Hiroshima University hi U i it 2

Contents Contents 1. 1. Introduction to the channeling effect Introduction to the channeling effect 2. 2. Motivation Motivation 3. 3. Experiment on electron beam deflection 3 E Experiment on electron beam deflection E i i t t l l t t b b d fl d fl ti ti (REFER, Hiroshima University) (REFER, Hiroshima University) 4. Experiment on proton beam deflection 4. Experiment on proton beam deflection (P (Proton Synchrotron, KEK) (Proton Synchrotron, KEK) (P t t S S h h t t KEK) KEK) 5. Possible applications at J 5 Possible applications at J 5. Possible applications at J PARC and ILC Possible applications at J-PARC and ILC PARC and ILC PARC and ILC 6. 6. Future experiments Future experiments 7. 7. Summary Summary 3

Introduction Introduction (channelling effect) (channelling effect) crystallographic plane y g p p atoms of crystal y θ θ crystal's axis positive particles � planar channeling negative particles � axial channeling negative particles � axial channeling θ < critical (Lindhard) angle � channeling effect θ > critical (Lindhard) angle � no channeling effect 4

Introduction Introduction (beam steering) (beam steering) • Deflection of POSITIVE particles by BENT crystal Deflection of POSITIVE particles by BENT crystal deflection angle • Deflection of NEGATIVE particles by STRAIGHT crystal Deflection of NEGATIVE particles by STRAIGHT crystal Deflection of NEGATIVE particles by STRAIGHT crystal Deflection of NEGATIVE particles by STRAIGHT crystal deflection angle 5

Introduction Introduction (beam steering) (beam steering) • Deflection of POSITIVE particles by BENT crystal using Deflection of POSITIVE particles by BENT crystal using volume reflection volume reflection l l fl fl ti ti 6

Motivation Motivation To develop techniques of beam handling systems using crystals • establishment of bent crystal systems for the proton beam f f separation • getting basic understanding for the electron beams (not so well studied as in case of protons) Future applications • proton beam separation at J-PARC (Japan Proton t b ti t J PARC (J P t Accelerator Research Complex) • electron beam collimation at ILC (International Linear Collider) • electron extraction system at the REFER ring (Relativistic • electron extraction system at the REFER ring (Relativistic Electron Facility for Education and Research) at HU 7

Experiment on electron beam deflection Experiment on electron beam deflection (REFER ring, Hiroshima University) (REFER ring, Hiroshima University) 8

REFER ring @ Hiroshima University REFER ring @ Hiroshima University REFER (Relativistic Electron REFER (Relativistic Electron Facility for Education Facility for Education Facility for Education Facility for Education and Research) and Research) 150-MeV electron beam injection line injection line QM3 beam extraction line magnet beam intensity: 1x10 4 s -1 9

REFER ring @ Hiroshima University REFER ring @ Hiroshima University 10

Extraction line Extraction line Experimental setup setup QM3 injection magnet line extraction extraction line 11

Schematic view of the setup Schematic view of the setup • the <100> axis was roughly aligned to the beam direction the beam direction • each combination of θ and φ angles and a beam profile at the FOS plate was recorded Fiber Optic plate p p with a Scintillator (FOS) thickness of Si crystal: 16 µ m t l 16 beam profile beam profile beam profile beam profile e – 150-MeV electron beam 150-MeV electron beam direction of direction of <100> axis <100> axis φ 2.3 m 2.3 m θ 12

Experimental setup Experimental setup extraction line thickness of crystal: 16 µ m y µ QM3 vacuum: 1.0x10 -7 torr QM3: quadruple magnet to change beam divergence at the crystal position 13

Setup Setup Phosphor +mirror Goniometer IIT & CCD Si crystal Beam Beam 14

Data Acquisition system Data Acquisition system The procedure of grabbing pictures and moving two goniometers was synchronized was synchronized with the beam gate. Pictures were taken only when electron beam hit the FOS plate the FOS plate. 15

Experiment: beam divergence Experiment: beam divergence Beam divergence as a function of QM3 current (it was estimated from the measurements and calculations of the optics of the beam line) (it was estimated from the measurements and calculations of the optics of the beam line) vertical horizontal d) d) nce, (mrad nce, (mrad m divergen m divergen beam beam current of QM3 magnet, (A) current of QM3 magnet, (A) Vertical angle dependence of the profile is changing in a range from 2.0 A to 2.6 A Lindhard angle for <100> axis of Si crystal: 0.7 mrad Beam divergence > Lindhard angle 16

Beam profiles Beam profiles QM3: 2.0 A, θ = 0, φ = -1.5 mrad QM3: 2.6 A, θ = 0, φ = -1.5 mrad Beam divergence: 3 0 mrad Beam divergence: 3.0 mrad Beam divergence: 5 2 mrad Beam divergence: 5.2 mrad 17

Analysis Analysis Vertical beam divergence: 3.0 mrad Projected beam profile was fitted with double Gaussian QM3: 2.0 A Q on, (mm) on rojectio al projecti vertica pr Beam center was determined as the weighted average in 2 σ region 18

Results Results (1) (1) Deflection angle = change of the beam center + 2.34 m Vertical beam divergence: 3.0 mrad θ =0 mrad (QM3: 2.0 A) ad) ngle, (mra eflection a de crystal angle φ , (mrad) 19

Results Results (2) (2) Vertical beam divergence: Vertical beam divergence: 3.8 mrad (QM3: 2.2 A). 5.2 mrad (QM3: 2.6 A). θ = 0 mrad θ = 0 mrad (mrad) (mrad) on angle, ( on angle, ( deflectio deflectio crystal angle φ , (mrad) y g φ , ( ) crystal angle φ , (mrad) y g φ , ( ) 20

Results Results (3) (3) Deflection vs. beam divergence Deflection vs. beam divergence e, (mrad) The magnitude of the deflection, Δ , was determined by fitting the plot with 1 st by g e p o magnitude derivative of Gaussian function eflection m Δ malized de norm beam divergence, (mrad) Larger beam divergence Larger beam divergence � Smaller deflection Smaller deflection 21

Simulation Simulation Lindhard string continuous potential Lindhard string continuous potential – Thomas-Fermi radius a – distance from <100> axis ρ – lattice constant, it is 5.43 A for Si lattice constant it is 5 43 A for Si d d Z 1 e – charge of incident particle – atomic number, 14 for Si Z 2 – Lindhard constant Sqrt[3] Lindhard constant Sqrt[3] C C Conditions for simulation Conditions for simulation • 4 th order of Runge-Kutta method • Without consideration of single and multiple scattering, channeling radiation and crystal imperfection and crystal imperfection • To save a computational time the incident angles of particles was limited to the twice of the Lindhard angle • Energy of electrons: 150 MeV • Thickness of the crystal: 16 µ m 22

Simulation: trajectory Simulation: trajectory Trajectory of the 150-MeV electrons inside of the Si crystal <100> axes <100> axes Initial position : X=-2.5 Å ,Y=-2.5 Å Initial position : X=0 Å ,Y=-2.5 Å p , p , X direction = 0.1 mrad X direction = 0.095 mrad Y direction = 0.01 mrad Y direction = 0.09 mrad 23

Simulation Simulation (1) (1) Beam divergence: 5.2 mrad Beam divergence: 3.0 mrad mrad) mrad) n angle, (m n angle, (m deflection deflection crystal angle φ , (mrad) t l l φ ( d) crystal angle φ , (mrad) t l l φ ( d) Larger beam divergence � Smaller deflection Larger beam divergence L L b b di di � S S Smaller deflection ll ll d fl d fl ti ti 24

Simulation Simulation (2) (2) Comparison with experimental data Beam divergence: 5 2 mrad Beam divergence: 5.2 mrad Beam divergence: 3 0 mrad Beam divergence: 3.0 mrad mrad) mrad) n angle, (m n angle, (m deflection deflection crystal angle φ , (mrad) t l l ( d) crystal angle φ , (mrad) t l l ( d) The tendency of the deflection as a function of the vertical direction of the crystal ( φ ) is same crystal ( φ ) is same. But, in quantitative comparison, the peak to peak But in quantitative comparison the peak-to-peak difference of the deflection angle of the measurement is about 0.4 mrad, while it’s around 0.04 mrad for the simulation. 25

Simulation Simulation (3) (3) The possible reason of quantitative difference is that in reality the electrons which travel in the crystal with angles more than Lindhard angle can also be trapped by the potential of the crystal while the angle can also be trapped by the potential of the crystal, while the simulation cannot take into account the processes for particles with the large beam divergence. Simulation which includes all physical processes should be performed. 26