UpstreamExtinctionMonitor

Plots

• Histogram
  • (1) Scattering Rate (n/mm^2/proton) vs Radius
    • All Charged Tracks
    • Tracks that Point to Foil
  • (2-1) Scattering Rate in the first PMT (1 coincidence) vs Radius - Cherenkov threshold passed
  • (2-2) Photoelectron Yield in the first PMT (1 coincidence) vs Radius - Cherenkov threshold passed (p.e.yield 187)
  • (3) 3-fold Coincidence Rate vs Radius - Cherenkov threshold passed
• Graph - pass "Tracks that Point to Foil"
  • (1) Particle Mean Energy vs Radius
    • Dominant particles: Proton, Pion, Electron (p.e.yield 187 for 3.8 GeV Proton Gun)
    • "Rare" particles: Kaon, Muon
  • (2) Nparticles vs Radius

Simulation of scattering in Ion Chamber using G4beamline

Part 1 (g4bl - "g4bl/"): Simulation in g4bl

Source code

vi g4bl/ICsimulation.g4bl

• Beam: gaussian, nEvents=1e07, particle = proton (M = 938.272 MeV, KE = 8000.0 MeV)

  6.2 beam --- This command places itself into the geometry

• Beam pipe: innerRadius = 38.1mm, radius=39.6mm

  6.92 tube / 6.93 tubs --- via place

• Ion Chamber (IC):

  Prototype: Ti =1= Al ==2== Al ====4==== Al ====4==== Al ==2== Al =1= Ti

  - material of spacers: Ar / CO2 (80 / 20%)

   material ArgCO2 Ar,0.80 CARBON_DIOXIDE,0.20 density=1.66*0.001
  

  - boxes to place:

  Ti Window -> box: 70mm * 70mm * 0.0015"
  Foil (Al) -> box: 70mm * 70mm * 0.004"
  Gas (spacers) -> box: 70mm * 70mm * (Nspacers*0.0625")

  box VacPlateF height=70.0  width=70.0  length=$LEN_VacPlate                color=0,1,1      material=Ti
  box ArCO2a    height=70.0  width=70.0  length=1*0.0625*25.4-$LEN_VacPlate  color=invisible  material=ArgCO2
  box GndPlateF height=70.0  width=70.0  length=$LEN_GndPlate                color=0,0,1      material=Al
  

• Virtual Detector:

  • innerRadius = 40mm (outer radius of beam pipe = 39.6mm), radius = 500mm
  • distance from IC: 1 m

  6.96 virtualdetector Construct a VirtualDetector that generates an NTuple --- via place

Run with g4blgui

1. Root-output mode: "Run" without "Visualization" (event rate: 13450 evt/s)
   Output -- "g4bl/g4beamline.root"

2. Visualization mode

Part 2 (ROOT macro - "root/"): Loop to find two distributions of detected/traced scattering particles

Get plots

root -l root/VDtoIC.C

• Charged particles (PDGid): electron (11), muon (13), pion (211), kaon (321), proton (2212)
• Histogram

  • (1) Distributions of scattering particle rates vs Radius

    1. All detected charged particles: "scatter"
       • Using $x$, $y$ for radius range division (binning) | $z$ fixed at VD
         $$r = \sqrt{x^{2} + y^{2}}$$
    2. Only charged particles traced back to IC: "scatterT"
       • Using $p_x$, $p_y$, $p_z$ to trace back a detected particle
       • Location at the plane of IC:
         $$x_1 = x - p_x\times\frac{1000}{p_z} $$ $$y_1 = y - p_y\times\frac{1000}{p_z} $$
       • Check if inside IC: (IC/foil geometry: 70mm(H) * 70mm(W) * (0.004 * 0.0625 * 25.4mm)(L)) $$|x_1| < 35 \quad\text{and}\quad |y_1| < 35$$
       • Check if inside beam pipe: (innerRadius = 38.1mm) $$r_1 = \sqrt{x_{1}^{2} + y_{1}^{2}} < 38.1$$

  • (2-1) Scattering Rate in the first PMT (1 coincidence) vs Radius

    • Tracks that Point to Foil
    • Pass Cherenkov threshold $$p > \frac{M}{\sqrt{n^2 - 1}}$$ (refractive index of Quartz: n = 1.47)
    • Integrate over cube area of the crystal: Area = 25mm*25mm
    • Multiply by the number of proton incidents on the IC: $10^{10}$ in a pulse or $10^{5}$ out of time ($10^{-5}$ extinction) $$Rate_\text{1PMT} = \text{Rate} \times \text{Area} \times N_\text{OOT}$$

  • (2-2) Photoelectron Yield in the first PMT (1 coincidence) vs Radius

    • Tracks that Point to Foil
    • Pass Cherenkov threshold
    • Integrate over cube area of the crystal: Area = 25mm*25mm
    • Multiply by the number of proton incidents on the IC: $10^{10}$ in a pulse or $10^{5}$ out of time ($10^{-5}$ extinction)
    • Multiply by p.e.yield 187 (for 3.8 GeV Proton Gun) $$Yield_\text{1PMT} = \text{Rate} \times \text{Area} \times N_\text{OOT} \times 187$$

  • (3) 3-fold Coincidence Rate vs Radius

    • Tracks that Point to Foil
    • Pass Cherenkov threshold
    • Using "Effective Area" AreaEff = $\frac{1}{4}\times$ Area
      • Assumption: point-like scattering from the center of the IC
      • The first PMT 1m downstream; The third PMT 2m downstream
    • Multiply by the number of proton incidents on the IC: $10^{10}$ in a pulse or $10^{5}$ out of time ($10^{-5}$ extinction) $$Rate_\text{3PMT} = \text{Rate} \times \text{AreaEff} \times N_\text{OOT}$$
• Graph

  • (1) Distribution of mean energies

    • Using $p_x$, $p_y$, $p_z$ and $M$ to calculate the particle energy (M_proton = 938.272 MeV, M_kaon = 493.677 MeV, M_pion = 139.6 MeV, M_muon = 105.7 MeV, M_electron = 0.511 MeV) $$E = \sqrt{{p_x}^{2} + {p_y}^{2} + {p_z}^{2} + M^{2}}$$
    • The mean particle energy $\bar{E_i}$ at a given radius $r_i$ $$\bar{E_i} = \frac{1}{\text{num of}j}\sum_{[r_i-5, r_i+5]} E_{j}$$

  • (2) Distribution of particle numbers

Output file

root --web=off -l root/rootfiles/ScatterDistribution.root

Part 3 (ROOT macro - "root/"): Draw plots saved in "root/figures/"

Histograms

Run

root -l root/drawHist.C

1. Scattering Rate vs Radius - "root/figures/Nscatter_compare_1e07.png"

2. OOT Conincidence Rate in PMT vs Radius - "Nscatter_compare_Cherenkov1e07.png"

Graph

Run

root -l root/drawGraph.C

1. Mean Energy vs Radius - "root/figures/MeanEnergy_vs_R_1e07_all.png"

• Dominant particles (Smooth): Proton, Pion, Electron
• "Rare" particles (Jagged): Kaon, Muon

2. Number of Particles vs Radius - "nParticles_vs_R_1e07_all.png"