1、Muon Flux Measurements and Simulation at CJPL,Zhi ZENG CDEX Collaboration,Symposium of the Sino-German GDT Cooperation,Tbingen, Apr. 2013,Contents,IntroductionMuon Flux MeasurementMuon Flux SimulationMuon Background in CJPLSummary,2018/9/23,1.Introdution,Muon Flux Measurements and Simulation at CJPL
2、,2018/9/23,第3页,The position of the Jinping tunnel,2018/9/23,第4页,Profile of Jinping Tunnel,2018/9/23,第5页,Elevation/m,Tunnel length/m,CJPL Tunnel,CJPL Tunnel,Jinping Mountain,Elevation/m,Yalong River（East）,Yalong River（west）,CJPL Site,2018/9/23,第6页,Traffic Tunnel A,Traffic Tunnel B,CJPL Entrance,Main
3、Hall,Total Volume,Muon Background in DM Exp.,Muon penetration;Neutrons produced by muon interactions;Gammas produced by muon interactions;Muon capture reactions(not important).,2018/9/23,第7页,2. Muon Flux measurement,Muon Flux Measurements and Simulation at CJPL,2018/9/23,第8页,Detector &Electronic sys
4、tem,2018/9/23,第9页,A telescope system consisting of 2 groups, both of them is composed of 3 plastic scintillation detectors. The signal from PMT is fanned into 2 channels: One fed into a 100MHz bandwidth FADC module, the other sent to logic OR modules after discriminated and stretched. A signal gener
5、ator as a random trigger for dead time study also contribute system trigger gate. FADC converts the whole analog pulses to digital signals, which written into storage for offline analysis by DAQ program.,20 cm,1.0m0.5m0.05m,Muon event selected: Pulse Shape Discrimination(PSD),2018/9/23,第10页,Muon ene
6、rgy deposit = 10MeV in 5cm thickness detector, while gamma deposit energy 99.9%,Using signal generator, serving as random trigger, produces periodic pulses which are independent of physics events.Dead time correction factor: Defined as the ratio of recorded number to generated number of random trigg
7、er events;Dead time correction factor: measured, higher than 99.9%.,2018/9/23,第14页,Muon Flux measurement correction,(2) Edge effect correction: 93.4%,Edge effect:Muon would pass the edge of the top or bottom scintillators but penetrate the whole thickness of the middle one. in thes cases, these even
8、ts would not pass pulse amplitude threshold selected.using Monte Carlo method to calculate the correction factor, it is 93.4%.,edge effect illustration,Muon Flux measurement correction,2018/9/23,第15页,(3) detection efficiency correction,(4) solid angle correction,muon Flux:,number of triple-coinciden
9、t events,2018/9/23,第16页,Muon Flux Measurement in CJPL,Nov. 2010 to Dec. 2011, 231 days measurement, 28 events from two groups are pass all the constrain.After correction, get Muon flux in CJPL*: (2.0 0.4) 10-10cm-2s-1* the solid angle correction in CJPL is set to 1.0 for the angle distribution under
10、ground is unkown.,2018/9/23,第17页,2018/9/23,第18页,3. Muon Flux simulation,Muon Flux Measurements and Simulation at CJPL,2018/9/23,第19页,Incident Muon Energy Spectrum,Assumption：muon energy spectrum on the top of Jinping mountain (4000 m) like that at sea level,2018/9/23,第20页,Fig.1 Muon momentum spectru
11、m distribution of two different angles at sea level 2,Gaisser Equation:,:Muon energy on sea level(GeV),Computational Model and program,Assumption: CJPL lies in a hemisphere MUSIC: muon transportation.,2018/9/23,第21页,Fig. 2 Schematic of the mountain and CJPLs location,Muon energy threshold:,Muon ener
12、gy 860GeV104GeV, integral muon flux in the ground is about 4.8410-8 cm-2s-1.,Simulation results by MUSIC,Average energy of residual muon : 370GeVMuon survival probability: 7.6510-3 Muon flux in CJPL with ：3.1710-10cm-2s-1 (simulation) 2.010-10 cm-2s-1 (measurement）,2018/9/23,第22页,Fig.3 Simulation re
13、sults of residual muon flux,2018/9/23,第23页,Google Earth map for the elevation of Jinping Mount.,voxeled JInping Mount in GEANT,Google Elevation API,pixel:201*301,CJPL,CJPL average rock overburden/m,exact simulation is processing!,polar angle/deg.,4. Muon Background in CJPL,Muon Flux Measurements and
14、 Simulation at CJPL,2018/9/23,第24页,Neutron by Muon with FLUKA,2018/9/23,第25页,Incident Muons,Rock,Air,Concrete,Schematic of computational model for secondary particles caused by muon,Neutron 20MeV,neutron 20MeV: 0.1321 -20MeV: 0.1323,8.3710-11 cm-2s-1,Neutron flux(by muon):,Gamma by Muon with FLUKA,2
15、018/9/23,第26页,Incident Muons,Rock,Air,Concrete,Schematic of computational model for secondary particles caused by muon,Gamma yield by muons: 49.52 p/,Gamma flux by muon :,1.5710-8 cm-2s-1,5. Summary,Muon Flux Measurements and Simulation at CJPL,2018/9/23,第27页,underground Labs in the world,2018/9/23,
16、第28页,第29页2018/9/23,2010中国锦屏地下实验室建设 及暗物质实验工作总结汇报会,Thanks！,References,1 Heusser, G., Low radioactivity background techniques, 1995, Annual Reviews Inc: Palo Alto, CA, USA. p. 543-543. 2Allkofer O C. Introduction to Cosmic Radiation, 1987, Science Press: Beijing. p.155-159.3A Bettini. Underground labor
17、atoriesJ. Nuclear Instruments and Methods in Physics Research A.2011, 626-627: S64S68.4M J Carson, J C Davies, E Daw, et al. Neutron background in large-scale xenon detectors for dark matter searchesJ. Astroparticle Physics . 2004,21: 667-687.5J.M Carmona, S Cebrin, E Garca, et al. Neutron backgroun
18、d at the Canfranc underground laboratory and its contribution to the IGEX-DM dark matter experimentJ. Astroparticle Physics .2004, 21: 523-533.6 F E Gray, C Ruybal, J Totushek, et al. Cosmic ray muon flux at the Sanford Underground Laboratory at HomestakeJ. Nuclear Instruments and Methods in Physics Research A .2011, 638: 63-66.,2018/9/23,第30页,
