Radiator. CBM-TRD TDR review 2017, March 14th. Cyrano Bergmann WWU Muenster, Germany

Transcription

1 Radiator CBM-TRD TDR review 207, March 4th WWU Muenster, Germany

2 MWPC Operation Principle 2

3 3 Optimization of the Chamber Nobel gas choice: Chamber absorption characteristic: TR-Production region

4 4 Radiator Simulation Effective description: dn 4 α exp N σ 2 = θn ϱ θn ϱ 2 θ n [ cos ϱ θ n ] d ω ω κ exp σ n ω l 2 ω P, i ϱi = γ ω 2c l κ= l2 2 π n ϱ κ ϱ 2 θ n= >0 κ ω P,i= Fabjan et al π α ρi N A Z i ℏ c Ai me / c 2 /2 l: foil thickness l2: gap thickness ri: density s: photon absorption cross section wp,i: plasma frequency TR-production chamber absorption x TR-detection = CBM TRD TDR Review TRD-TDR review

5 5 Radiator Classes Regular Foil Stack high regularity high yield due to interference need mechanical support Irregular Foam Irregular Fibers low regularity complex structure fully irregular low interference minimal interference self-supporting self-supporting

6 7 Material Density: r and r2 dn 4 α e N σ = θ n σ n ϱ θ n ϱ 2 θn d ω ωκ e f TR-production 2 [ cos ϱ θ n ] TR-absorption by 20 prototype ωl ω ϱ i= 2 ωp, i 2c γ 2, ne, i e2 ω P,i =, ϵ0 me ρi N A Z n e,i = A literature value only small influence of r2 due to factor 000 smaller values literature value

7 Lorentz-Factor: g dn 4 α e N σ = θ n n ϱ θ ϱ 2 θn d ω ωκ e σ n f TR-production 2 [ cos ϱ θ n] 8 ωl ω ϱ i= 2 ωp, i 2c γ 2, TR-absorption by 20 prototype Saturation around g = 5.0 Threshold around g = 0.5

8 9 Foil Thickness: l N f σ dn 4 α e = θ n n ϱ θ ϱ 2 θn d ω ωκ e σ n TR-production 2 [ cos ϱ θ n ] l2, l 2 π n ϱ κ ϱ 2 θ n= >0, κ κ= TR-absorption by 20 prototype Complex interference pattern Highest emission probability between 9 and 8 µm Parameter distribution unknown for irregular prototypes Approximate mean value from sample Large uncertainty for irregular radiators

9 0 Gap Thickness: l2 N f σ dn 4 α e = θ n n ϱ θ ϱ 2 θn d ω ωκ e σ n TR-production 2 [ cos ϱ θ n ] l2, l 2 π n ϱ κ ϱ 2 θ n= >0, κ κ= TR-absorption by 20 prototype Broad maximum between 700 and 200 µm Parameter distribution unknown for irregular prototypes Approximate mean value from sample Large uncertainty for irregular radiators

10 Number of Foils Nf N f σ dn 4 α e = θ n n ϱ θ n ϱ 2 θ n d ω ωκ e σ TR-production 2 [ cos ϱ θ ] n TR-absorption by 20 prototype TR-yield increases continuously Large uncertainty for irregular radiators

11 2 Regular Prototypes B: POKALON N470 C: Polypropylene D: Polypropylene E: Polyethylene F: Polyethylene FFM: Polyethylene Polyethylene C2H4n Polypropylene C3H6n POKALON N470 C6H4O3n

12 Mixed Prototypes 3 Self-Supporting PE Foam Foil Spacer Mixed Radiator Self-Supporting Micro-structured Foil Radiator

13 Irregular Prototypes PMMA PP PE PE PE PE PMMA PMMA PE PE PE 4

14 5 Mean E-Loss per Electron Nf=200, p=2gev/c Regular radiators <de/dxtr> kev <de/dxtr> kev Irregular radiators max. n TR-photons Polyethylene/ Polypropylene <de/dxtr> kev max. E-Loss <de/dxtr> kev Polyethylene/ Polypropylene POKALON N470 PolyMethylMethAcrylate

15 Pion Efficiency 6 at 90% Electron Efficiency and 0 hits per track Nf=200, p=2gev/c Regular radiators C, D max. E-Loss max. n TR-photons pion efficiency % Polyethylene/ Polypropylene pion efficiency % x E FFM Polyethylene/ Polypropylene POKALON N470 pion efficiency % F pion efficiency % x x Irregular radiators PolyMethylMethAcrylate

16 Testbeam Setup at CERN PS 202 7

17 Pion 3GeV/c 202 Münster Prototype 2mm 28 Pokalon PE foam PE foil PP fiber Design goal SIS00 Design goal SIS300 G K SI S FFM FFM 0 0 H B Approximated pion efficiency with 4 detector hits per 90% electron efficiency CBM TRD TDR Review

18 Real-Size Prototypes CBM TRD TDR Review 29

19 Summary 30 CBM-TRD radiator design: - Evaluation of optimal radiator parameters based on simulation - Production of radiator prototypes regular, foam and fiber - In beam test and comparison to simulation fine tuning of simulation Default radiator: Polyethylene foam foil radiator - Mechanical self-supporting - High TR-production performance - Soft TR-spectrum good matching to chamber absorption - Low material budget.39.75% X/X0 - Affordable price - First full size 57cm x 57cm x 35cm demonstrators built CBM TRD TDR Review