RTPC 12 Simulation. Jixie Zhang Aug 2014

Transcription

1 RTPC 12 Simulation Aug

2 Outline Try to answer the following questions: 1) What is the highest luminosity we can realistically achieve (including trigger and DAQ rates), and how big of a problem will random hits and multiple tracks create (latency, ambiguities, degradation of tracking etc.)? 2) How sensitive are we to backgrounds (noise, "hot channels", Moeller electrons, photons, pions, and other particles) and how can we minimize them? 3) What kind of resolution in momentum can we achieve (as a function of momentum and angle)? 4) What is a realistic momentum range over which we can reliably detect, identify and measure the momentum of protons? 5) Particle ID: how reliably can we measure de/dx (e.g., for the GEM design, how can we improve gain homogeneity and stability)? How well can we separate protons from pions, deuterons etc. and how well can we separate 3He from 3H and 4He? 6) What is the maximum total acceptance in theta, phi and p we can achieve? Blue color items will be answered in this talk! 2

3 Numbers in the proposal RTPC length = 40 cm RTPC Drift Distance > 4cm RTPC resolution: dz<3mm dp<10 MeV/c, d pq<2 deg Beam time: 35 days on D2 and Luminosity 2.0E34 #/s/cm^2 3

4 Max Luminosity and Beam Current Take the following numbers: D2 gas at 7.5 ATM, 300K --> 40 cm in length Beam current 220 na =1.229 mg/cm^3 L_target = 4.0E34 #nuclons/s/cm^2 Exit cap 10 um Aluminum ( =2.7 g/cm^3) L_exit = 2.2E33 #nucleons/s/cm^2 for I = 220 na Entrance cap 10 um Aluminum ( =2.7 g/cm^3) L_entrance = 2.2E33 #nucleons/s/cm^2 for I = 220 na Beam Exit window 10 um Beryllium ( =1.85 g/cm^3) L_beamwindow = 1.5E33 #nucleons/s/cm^2 for I = 220 na Hall-B beam line can deliver 800 na current, and CLAS12 can take L=1.0E35, (L_target + L_exit + L_entrance + L_beamwindow)/220 * I_max = 1.0E35 --> The maximum beam current (consider target, caps and beam exit window) we can use is: I_max ~= 480 na, or neutron Luminosity = 4.4E34 4

5 Max Luminosity and Beam Current Take the following numbers: D2 gas at 7.5 ATM, 300K --> 40 cm in length Beam current 220 na =1.229 mg/cm^3 L_target = 4.0E34 #nuclons/s/cm^2 Exit cap 100 um Aluminum ( =2.7 g/cm^3) L_exit = 2.2E34 #nucleons/s/cm^2 for I = 220 na Entrance cap 100 um Aluminum ( =2.7 g/cm^3) L_entrance = 2.2E34 #nucleons/s/cm^2 for I = 220 na Beam Exit window 10 mil Beryllium ( =1.85 g/cm^3) L_beamwindow = 3.9E34 #nucleons/s/cm^2 for I = 220 na Hall-B beam line can deliver 800 na current, and CLAS12 can take L=1.0E35, (L_target + L_exit + L_entrance + L_beamwindow)/220 * I_max = 1.0E35 --> The maximum beam current (consider target, caps and beam exit window) we can use is: I_max ~= 180 na, or neutron Luminosity = 1.6E34 5

6 RTPC12 in Geant4 Target: D2 gas, 300k, 7.5 ATM, 5 mm radius, 40 cm long Target Wall: 25 um kapton Drift Region: 3<R<8 cm Drift Gas: 300k, 1 ATM, He/DME (80/20) Use carbon fiber (3.5 x 2 mm) as rib to support Mylar foils phi coverage = 350 degrees Threshold = 59 MeV, barely reach drift region 6

7 RTPC12 in Geant4 Target: D2 gas, 300k, 7.5 ATM, 5 mm radius, 40 cm long Target Wall: 25 um kapton Drift Region: 3<R<8 cm Drift Gas: 300k, 1 ATM, He/DME (80/20) Use carbon fiber (3.5 x 2 mm) as rib to support Mylar foils phi coverage = 350 degrees Might need to add support ribs... 7

8 COMPASS GEM 2-D Readout Time resolution: 12 ns (using 25 ns sampling APV25 readout) Space resolution: 70 um We will use DREAM chips with 25 ns time sampling in the readout Pad or u-v double-layer strips? How long is each strip? 8

9 RTPC Theta various Pad Size Main feature: Drift Region = 3<R<8 cm Readout pad strips R=9cm theta reconstruction resolution for RTPC tracks Time resolution: 12 ns (using 25 ns sampling DREAM readout) RTPC hit resolution in cylindrical coordinate: S resolution ds =0.07 mm, which is corresponding to 12ns drift distance. Angle resolution for hits reconstruction: d = RTPC_Pad_W/sqrt(12)/RTPC_ReadOut_R. For 4.5(w)x5(z) pad: d 14.4 mrad, or 0.83 degrees. For 2(w)x2(z) pad: d = 6.4 mrad, or 0.37 degrees. Zhang or 0.07 degrees 9 For x-y stripes 2-D readout: d 1.3Jixie mrad, Z resolution dz = RTPC_Pad_Z/sqrt(12)

10 RTPC Performance: 4.5x5 mm pad Only thrown at z=0 for a quick demonstration See their dependencies on other variables in next 3 pages. 10

11 P Resolution: 4.5x5 mm pad Sigma Mean Only thrown at z=0 for a quick demonstration 11

12 Theta Resolution: 4.5x5 mm pad 12

13 Phi Resolution: 4.5x5 mm pad 13

14 Phi Reconstruction Try to improve phi angle reconstruction by 1-D function of f(p) or g(theta), but it does not work. It should be corrected by 2-D function h(p,theta). Need to write Minuit code to do the job. (Future job) 14

15 RTPC Performance: 2x2 mm pad Only thrown at z=0 for a quick demonstration See their dependencies on other variables in next 3 pages. 15

16 P Resolution: 2x2 mm pad Sigma Mean 16

17 Theta Resolution: 2x2 mm pad 17

18 Phi Resolution: 2x2 mm pad Phi reconstruction is bad! But can be improved. See details in next page. 18

19 RTPC Performance: 2-D readout Only thrown at z=0 for a quick demonstration See their dependencies on other variables in next 3 pages. 19

20 P Resolution: 2-D readout Sigma Mean 20

21 Theta Resolution: 2-D readout 21

22 Phi Resolution: 2-D readout Phi reconstruction is bad! But can be improved. See details in next page. 22

23 Compare P Resolution 4.5x5 mm pad 2x2 mm pad BoNuS6 RTPC 23 2-D readout

24 Particle Identification Throw 10k particles of each type randomly in range of [0.02,0.35] Assuming 2x2 pad Using proton reconstruction code to reconstruct 3He 24

25 2x2 mm pad Full length in Z RTPC Acceptance Averaged over all Z! This figure is for demonstration only! Should provide 4-D maps 25

26 Number of Channels Common feature: Drift Region = 3<R<8 cm Readout pad strips R=9cm Time resolution: 12 ns (using 25 ns sampling DREAM readout) Option 1: Option 2: Option 3: Option 4: Option 5: 4.5 x 5.0 mm pad --> 2.0 x 2.0 mm pad --> (550x0.4) (0.4x400) mm x-y strips --> (110x0.4) (0.4x80) mm x-y strips --> ( 55x0.4) (0.4x40) mm x-y strips --> 122 x 80 = 9760 channels 274 x 200 = channels = 2374 channels 5x x1000 = x x1000 = (need to study total rates (bg+sigma) to make further decision) DAQ Cost: ~1 dollars per channel 26

27 Summary 1) What is the highest luminosity we can realistically achieve (including trigger and DAQ rates), and how big of a problem will random hits and multiple tracks create (latency, ambiguities, degradation of tracking etc.)? Highest luminosity is 1.0E35 neuclons/s/cm^2 for CLAS12 at 180 na beam current, or 1.6E34 neutrons/s/cm^2 for RTPC12. 2) How sensitive are we to backgrounds (noise, "hot channels", Moeller electrons, photons, pions, and other particles) and how can we minimize them? (In progress) 3) RTPC momentum resolution and valid reconstruction range depend on readout pad size. Assuming 5 cm drift distance and readout locates at R=9cm, For pad 4.5x5.0 mm, the dp resolution is 10 MeV for 150 MeV/c proton. For pad 2.0x2.0 mm, the dp resolution is 10 MeV for 200 MeV/c proton. For compass 2-D readout, the dp resolution is 10 MeV for ~290 MeV/c proton. 4) What is a realistic momentum range over which we can reliably detect, identify and measure the momentum of protons? See the answer to 3). 5) Particle ID: how reliably can we measure de/dx (e.g., for the GEM design, how can we improve gain homogeneity and stability)? How well can we separate protons from pions, deuterons etc. and how well can we separate 3He from 3H and 4He? Proton can be separated easily from pion, 3He and 4He. Might have Kaon contamination. 6) What is the maximum total acceptance in theta, phi and p we can achieve? For pad 2.0x2.0 mm: 350 degrees for phi, 15<theta<165, 60<P<200 27

28 Back up 28

29 RTPC6 Performance: 4.5x5 mm pad Only thrown at z=0 for a quick demonstration See their dependencies on other variables in next 3 pages. 29

30 RTPC6 P Resolution: 4.5x5 mm pad Sigma Mean 30

31 RTPC6 Theta Resolution: 4.5x5 mm pad 31

32 RTPC6 Phi Resolution: 4.5x5 mm pad 32

33 What is DREAM? Based on AMS 0.35 um CMOS technology 64 channels in each chip Will be used in the forward tracker of the central detector of the CLAS12 Design dead time: 10^-7 for 4 samples/event readout, 40 khz trigger rate and 16 us trigger latency Dead-timeless Readout Electronics ASIC for Micromegas R&D is now carried out in CEA/IRFU. Bernd Surrow in Temple University also cooperate with them to do R&D of using this readout for GEM detectors for EIC projects. 33

34 More about DREAM chips 34

35 GEM vs MicroMeGas No obvious difference Readout used for Micromegas can also be used for gems. 35

36 DREAM vs APV25 APV25 is no longer in production. DREAM chip is still under R&D, but is closed to production stage (M. Garcon). 36

37 Other thoughts Reduce the thickness of the first two silicon layers from 300 um to 50 um in the Central Tracker of CLAS12 Replace gem layers by 50 um silicon layers Reach layer3: 98 MeV Reach layer2: 87 MeV Reach layer1: 69 MeV Momentum threshold of protons that Jixiepenetrate Zhang silicon layers (50 um each layer) 37

38 Drift Velocity (Unit: km/s) 38

39 Number of e-ion pairs 39