Optimized Target Parameters and Meson Production by IDS120h with Focused Gaussian Beam and Fixed Emittance (Update) X. Ding, UCLA AAG June 27, /27/12

Focused Incident Proton Beam at 8 GeV (Beam radius is fixed at 0.12 cm at z=-37.5 cm) 26/27/12 Relative normalized meson production is 0.84 of max at β* of 0.3 m for  x =  y = 5  m. For low β* (tight focus) the beam is large at the beginning and end of the interaction region, and becomes larger than the target there.

Focused Incident Proton Beam at 8 GeV (Cont’d) (Beam radius is fixed at 0.12 cm at z=-37.5 cm) Non-Linear Fit (Growth/sigmoidal, Hill) Y=N/(1+K2/beta -2 ) N=1.018 Sqrt(K2)= Linear emittance is 5 μm with beam radius of cm and β* of 0.3 m. 36/27/12

Gaussian distribution (Probability density) In two dimensional phase space (u,v): where u-transverse coordinate (either x or y), v = α u+β u ’ α, β are the Courant-Snyder parameters at the given point along the reference trajectory. In polar coordinates (r, θ): u = r cosθ v = r sinθ u ’ = (v-α u)/β=(r sinθ-α u)/β 6/27/124

Distribution function method Random number generator: Θ = 2π*rndm(-1) R = sqrt(-2*log(rndm(-1))*σ 6/27/125

Gaussian distribution (Fraction of particles) The fraction of particles that have their motion contained in a circle of radius “a” (emittance ε = π a 2 /β) is 6/27/126

Fraction of particles k=a/σε Kσ F Gauss 1π (σ) 2 /β39.5% 2π (2σ) 2 /β86.4% 2.5π (2.5σ) 2 /β or ~ 6π σ 2 /β95.6% Normalized emittance: (βγ)ε Kσ 6/27/127

Focused beam Intersection point (z=-37.5 cm): α * = 0, β *, σ * Launching point (z=-200 cm): L = = cm α = L/β * β = β * + L 2 /β * σ = σ * sqrt(1+L 2 /β *2 ) These relations strictly true only for zero magnetic field. 6/27/128

Setting of simple Gaussian distribution INIT card in MARS.INP (MARS code) INIT XINI YINI ZINI DXIN DYIN DZIN WINIT XINI = x0 DXIN = dcx0 YINI = y0 DYIN = dcy0 ZINI = z0 DZIN = dcz0 = sqrt(1-dcx0 2 -dcy0 2 ) (Initial starting point and direction cosines of the incident beam) 6/27/129

Setting with focused beam trajectories Modeled by the user subroutine BEG1 in m1510.f of MARS code x v or x h (transverse coordinate: u); x' v or x' h (deflection angle: u ’ ) XINI = x 0 + x h DXIN = dcx 0 + x’ h YINI = y 0 + x v DYIN = dcy 0 + x’ v ZINI = z 0 DZIN = sqrt(1-DXIN 2 -DYIN 2 ) 6/27/1210

Optimization of target parameters Fixed beam emittance (ε Kσ ) to π (σ) 2 /β Optimization method in each cycle (Vary beam radius or beam radius σ *, while vary the β * at the same time to fix the beam emittance; Vary beam/jet crossing angle; Rotate beam and jet at the same time) We also optimized the beam radius and target radius separately (not fixed to each other). 6/27/1211

Optimized Target Parameters and Meson Productions at 8 GeV (Linear emittance is fixed to be 4.9 μm ) Radius (cm) Beam/jet crossing angle (mrad) Beam angle/Jet angle (mrad) Initial0.404 (target) / st Run0.525 (target)25120/145 Old 2 nd Run (vary target radius and beam radius is fixed to be 0.3 of target radius) (target) /145.4 New 2 nd Run (vary beam radius with fixed target radius of cm; vary target radius with fixed beam radius of 0.15 cm.) Beam radius: 0.15 Target radius: / /27/1212

Optimize beam radius and target radius separately (Linear emittance is fixed to be 4.9 μm ) 6/27/1213 We found almost no improvement in optimized meson production if the beam radius is not fixed at 30% of target radius and optimized separately!

Optimized Meson Productions at 8 GeV (Linear emittance is fixed to be 5 μm ) Gaussian DistributionMeson Production Simple (0.404cm/20.6mrad/117mrad) Focused beam with fixed beam radius of cm at z=-37.5 cm (0.404cm/20.6mrad/117mrad) (-15.6% less than Simple) Focused beam with fixed Emittance at 5 μm (0.544cm/25.4mrad/120mrad) (-7.8% less than Simple) (8.9% more than Focused beam of radius at cm) Focused beam with fixed Emittance at 5 μm (0.15 cm (beam)/0.54cm(target)/26.5mrad(crossing)/1 27mrad(beam) /27/1214

Optimized Target Parameters and Meson Productions at 8 GeV (Linear emittance is fixed to be 10 μm ) Beam Radius (cm) Target Radius (cm) Beam/jet crossing angle (mrad) Jet angle (mrad) Initial0.404* st Run nd Run /27/1215 Gaussian DistributionMeson Production Focused beam with fixed Emittance at 10 μm ( cm (beam)/0.65cm(target)/32mrad(crossing)/135 mrad(beam) (-15% less than Simple) (60 % more than Focused beam of radius at cm )

Procedure of Simulation without Angular Momentum 1). Create a beam (simple Gaussian or focused) with target radius of cm, beam angle of 117 mrad and jet angle of mrad at z=-37.5 cm. 2). Track back the beam to z=-200 cm under the SC field and no HG Jet. 3). Based on the backward beam at z=-200 cm, create the forward beam at z=-200 cm. 4). Read the forward beam and run MARS15. 6/27/1216

Procedure of Simulation without Angular Momentum (Cont’d) Meson production with emittance of 5 μm is *10^5. (Old Method with single centroid particle track back and using Twiss formulae at z=-200 cm w/t SOL field, Meson production is *10^5.) 6/27/1217

Meson Productions without Angular Momentum 6/27/1218

Formulae Related with Angular Momentum q=1.6  (C), c = 3  10 8 (m/s) 1 (GeV) = (10 9  1.6  ) (J) = (10 9  q) (J) 1 (J) =1/(10 9  q) (GeV)  Px= qBcy/2 (J)  Py= -qBcx/2 (J)  Px=Bcy/(2  10 9 ) (GeV)~0.15By (GeV)  Py=-Bcx/(2  10 9 ) (GeV)~-0.15Bx (GeV) 6/27/1219

Estimation of Angular Momentum Effect Proton Beam: E0= GeV KE=8 GeV ET= GeV P=(ET 2 -E0 2 ) 1/2 = GeV (x0,y0,Px,Py), without angular momentum (x0,y0,Px+  Px,Py+  Py), with angular momentum 6/27/1220

Estimation of Angular Momentum Effect (Cont’d) Z = cm, B ~ T Z = -50 cm, B ~ T Z = -100 cm, B ~ T Z = -150 cm, B ~ T Z = -200 cm, B ~ T Pz = (P 2 -(Px+  Px) 2 -(Py+  Py) 2 ) 1/2 6/27/1221

Procedure of Simulation with Angular Momentum 1). Create simple Gaussian distribution at cm. 2). Transform each particle according to px -> px + qBy/2, py -> py> - qBx/2, using the x and y of the individual particle. (Use the B at the point we generate the particles, so cm) 3). Track the resulting distribution backwards to z=-50 cm,-100 cm, -150 cm and -200 cm under the SC field and no HG Jet. Based on this, create the forward beam at different position. 4). Read the forward beam and run MARS15. 6/27/1222

Procedure of Simulation with Angular Momentum (Cont’d) Meson production (simple Gaussian distribution) without angular momentum for launching point at z=-200 cm is *10^5. 6/27/1223 Launching pointMeson Production Z=-200 cm89179 Z=-150 cm91952 Z=-100 cm92783 Z=-50 cm98840

BackUp 6/27/1224

Courant-Snyder Invariant 6/27/1225

Emittance (rms) and Twiss Parameters 6/27/1226

Effect of Solenoid Field [Backtrack particles from z = cm to z = cm.] (Could then do calculation of α, β, σ at z = -200 cm, but didn’t) 6/27/1227

Effect of Solenoid Field 6/27/1228