WP2 Background WP2 Background simulations: progress of simulations: progress of
the workthe work
G. Luzón, JRA1 Meeting, Zaragoza,10-11 June 2006
JRA1-WP2JRA1-WP2
N3-BSNSN3-BSNSJRA2(IDEA)JRA2(IDEA)
WP3-B1WP3-B1
Development of a standard Development of a standard library of background library of background
simulation codessimulation codes
Background Background Simulation, Simulation,
Neutron-ShieldNeutron-Shield and Muon-Vetosand Muon-Vetos
Study on Study on CosmogenicCosmogenic
Induced ActivityInduced Activity
G. Luzón, JRA1 Meeting, Zaragoza,10-11 June 2006
General issuesGeneral issues
G. Luzón, JRA1 Meeting, Zaragoza,10-11 June 2006
Planning for this third year
• Analysis of data collected in the background monitoring campaign with MC codes
• Optimisation of the codes
Tasks
Tasks
• Design and implementation of the library
– Standard codes for specific task
– End-to-end simulation tool for experiments.
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Analysis of collected dataand optimisation of codes
G. Luzón, JRA1 Meeting, Zaragoza,10-11 June 2006
Muon simulations and MUSUN
• Muon backgrounds at Super-Kamiokande, KamLAND and CHOOZ are calculated using MUSIC (hep-ph/0604078 ) – Use of digital maps and mountain profile– Real composition of the rock (approximate in
CHOOZ)– Modified Gaisser atmospheric muon parametrization
in the large angle and small energy regimes– Well tested Monte Carlo integration method
G. Luzón, JRA1 Meeting, Zaragoza,10-11 June 2006
Average muon intensity versus depth: experimental and simulated (standard and modified Gaisser parametrization)
G. Luzón, JRA1 Meeting, Zaragoza,10-11 June 2006
Perfect agreement simulation/experiment (Cherenkov detector covering the entire solid angle)
Exp Stand. rock
G. Luzón, JRA1 Meeting, Zaragoza,10-11 June 2006
•Not so good agreement simulation/experiment (Two RPC plates)•Better agreement in the simulated experiment
G. Luzón, JRA1 Meeting, Zaragoza,10-11 June 2006
3 1.88
0.75 0.214x10-5
Quite good agreement regarding fluxes
G. Luzón, JRA1 Meeting, Zaragoza,10-11 June 2006
G4 muon simulation and LSC measurements
GOAL
To help in the understanding and interpretation of muon measurements in Zaragoza and Canfranc
FEATURES• Code: GEANT4 simulation, including standard electromagnetic processes for muons (Multiple Scattering, Ionisation, Bremsstrahung, Pair production, - Capture)
• Geometry: two plastic scintillators 40x80x5.08 cm3 (BC408) with different air separations, according to measurements
• Primary particles: muons with energy spectrum and angular distribution corresponding to Zaragoza (sea level) and Canfranc depth
• Output: energy deposits in each of the two detectors registered to perform off-line coincidence analysis with ROOT
G. Luzón, JRA1 Meeting, Zaragoza,10-11 June 2006
RESULTS: Zaragoza• Angular distribution: I α cos2
• Energy spectrum: mean energy ~4 GeV, f(E)=N0 if E<E0, f(E)=0.14E-2.7 if E>E0
Detector configuration: without air between them
G. Luzón, JRA1 Meeting, Zaragoza,10-11 June 2006
Registered energy spectra in top and bottom detectors
energy (MeV)
G. Luzón, JRA1 Meeting, Zaragoza,10-11 June 2006
RESULTS: Zaragoza• Angular distribution: I α cos2
• Energy spectrum: mean energy ~4 GeV, f(E)=N0 if E<E0, f(E)=0.14E-2.7 if E>E0
Detector configuration: without air between them
• ~91% of detected muons produce coincidences
• ~2.5% of muons give energy deposits under 3 MeV in coincidence spectra
• ratio of muons below and above the peak energy: ~0.064 in coincidence spectra
This ratio is in quite good agreement with experimental data
Detector configuration: 95 cm air between them
• only ~16% of detected muons produce coincidences
This reduction is in good agreement with experimental data
G. Luzón, JRA1 Meeting, Zaragoza,10-11 June 2006
RESULTS: Canfranc• Angular distribution: I α cos3.6, corresponding to a depth of ~850 m of standard rock
C. T. Stockel, J. Phys. A (Gen. Phys.) 1969, vol. 2 p. 639
• Energy spectrum: sampled from Lipari distribution for the Canfranc depth, mean energy 216 GeV
P. Lipari and T. Stanev, Phys. Rev. D 44 (1991) 3543
G. Luzón, JRA1 Meeting, Zaragoza,10-11 June 2006
RESULTS: Canfranc• Angular distribution: I α cos3.6, corresponding to a depth of ~850 m of standard rock
C. T. Stockel, J. Phys. A (Gen. Phys.) 1969, vol. 2 p. 639
• Energy spectrum: sampled from Lipari distribution for the Canfranc depth, mean energy 216 GeV
P. Lipari and T. Stanev, Phys. Rev. D 44 (1991) 3543
Detector configuration: 1 cm air between them
G. Luzón, JRA1 Meeting, Zaragoza,10-11 June 2006
Registered energy spectra in top and bottom detectors
energy (MeV)
G. Luzón, JRA1 Meeting, Zaragoza,10-11 June 2006
RESULTS: Canfranc• Angular distribution: I α cos3.6, corresponding to a depth of ~850 m of standard rock
C. T. Stockel, J. Phys. A (Gen. Phys.) 1969, vol. 2 p. 639
• Energy spectrum: sampled from Lipari distribution for the Canfranc depth, mean energy 216 GeV
P. Lipari and T. Stanev, Phys. Rev. D 44 (1991) 3543
Detector configuration: 1 cm air between them
• ~92% of detected muons produce coincidences
• ~2% of muons give energy deposits under 3 MeV in
coincidence spectra
• ratio of muons below and above the peak: ~0.058 in
coincidence spectra
This ratio is lower than in preliminary experimental data: to be understood
Design of specific codes
G. Luzón, JRA1 Meeting, Zaragoza,10-11 June 2006
Zeplin III
• Its performance have been studied using an end-to-end simulation tool based on G4 code
• To appear in Astroparticle Phys.
G. Luzón, JRA1 Meeting, Zaragoza,10-11 June 2006
ZEPLIN-III Software
• It models the instrument response to radioactive backgrounds and calibration sources– Generation– Ray tracing and detection– Processing by data acquisition electronics
• The package builds upon previous G4 advanced example “Underground Physics” by A. Howard and H. Araújo.
G. Luzón, JRA1 Meeting, Zaragoza,10-11 June 2006
S1 and S2 energy spectra in the inner 8 kg from collimated 57Co sourcelocated above the detector. S2 (shaded) is scaled down by a factor of 1000. Thecontribution of the individual energies (122.1 keV and 136.5 keV) is also shown.
Calibration
G. Luzón, JRA1 Meeting, Zaragoza,10-11 June 2006
Discrimination power•S2/S1 distributions for electrons (upper population) and nuclear recoils (lower population).• The thick lines represent the boundaries for a given -ray discrimination efficiency.
G. Luzón, JRA1 Meeting, Zaragoza,10-11 June 2006
With a WIMP-nucleon cross-section sensitivity of ~ 5 × 10−9 ZEPLIN-III would compete favourably with much larger targets and more expensive technologies being considered around the world.
Results
Activities and news
G. Luzón, JRA1 Meeting, Zaragoza,10-11 June 2006
Reports and presentations
• Technical report on WP1 included in the JRA1 annual report and presented in the Third ILIAS General Meeting (Gran Sasso, 29 February 2006)
G. Luzón, JRA1 Meeting, Zaragoza,10-11 June 2006
Publications
• A. Tang et al, Muon Simulations for Super-Kaiokande, KamLAND and CHOOZ, hep-ph/0604078
• H. Araújo et al., The ZEPLIN-III dark matter detector: performance study using an end-to-end simulation tool, to appear in Astroparticle Phys.
G. Luzón, JRA1 Meeting, Zaragoza,10-11 June 2006
Letter to G4 team• In collaboration with the MaGe group
– Long-standing bugs havegone unfixed:
• the Inelastic/ CrossSection/ 32_70|72|73|74|76_Ge have been removed • Bug 799 describes an inelastic interaction between a proton and an
alpha in which 55 MeV goes "missing" • Apparent non-generation of residuals for Ge(n,2n) reactions, which
leads to discrepancies in the statistics of inelastic recoils • …
– We ask them to change the “priority code” of our problems
offering them our help.
G. Luzón, JRA1 Meeting, Zaragoza,10-11 June 2006
News
• Released of G4 8.1 (June 2006). Changes:– New data
• G4EMLOW 4.0– Old data does not reproduce detection in gas at
atomic shell edges (Rob Veenhof) (¿new?)
• G4NDL 3.9– Added data for Antimony, Hafnium, Technetium,
Samarium, Neodymium and Gadolinium. – Updated inelastic data for 17_nat_Chlorine,
28_62_Nickel and removed data for 32_70/2/3/4/6_Germanium.