Summary TG10

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Summary TG-10 MC Background
Xiang Liu for TG-10
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Last Collab. Meeting
Joint MC force from Gerda Majorana.

• Detailed simulation of Gerda.
• Complete event MC information.
• trajectories all particles in GEANT4
  simulation.
• hits energy deposits from
  particles in sensitive volume.
• Radioactive backgrounds, muon veto, neutron.

Gerda Collab. , Jun 27-29, 2005
Last Collaboration meeting
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Outline

• Achievement since then
• MaGe update
• Gerda related Background Calibration
  sources
• RD related H-M crystals, LArGe
• Verification (Comparison) with SHIELD
• Analysis Pulse shape simulation analysis
• Summary Outlook

Gerda Collab. , Jun 27-29, 2005
outline
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MaGe Ready!
An internal note describing MaGe is ready.
First official version soon, MaGe ready for
users.
? MaGe ready to answer questions from other TGs!
Version releasing procedure being established.
Gerda Collab. , Jun 27-29, 2005
1) Further MaGe development
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2) Gerda Background Calibration
Top scintillator veto water cerenkov veto of
cosmic muon ? C. Tomei (LNGS) Water
Cerenkov veto optimization of PMT ? M.
Knapp (Tuebingen), A. Klimenko (Dubna) Cerenkov
veto, fine tuning GEANT4 energy threshold
? M. Bauer (Tuebingen) Transportation
shielding ? S. Belogurov Radioactive bg.
(Phase I) ? S. Schoenert Radioactive bg. (Phase
II) ? K. Kroeninger (MPI Munich) Ra
contamination in water ? L. Pandola
(LNGS) Calibration source for Gerda ? K.
Kroeninger
muon
radioactive
calibration
Gerda Collab. , Jun 27-29, 2005
2) Gerda Background
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Analysis of bkgd contributions from support
structure (Phase-I)
MaGe Geant4 MC probabilities per decay to
deposit energy at Q?? in 1 keV energy bin
Co-60 1.6 10-5 Bi-214 1.2 10-5 Tl-208 5.8
10-5
Co-60 3.1 10-5 Bi-214 1.3 10-5 Tl-208 7.5
10-5
Using our limits for Cu, PTFE and Si Rate in
roi lt1.510-3 / (keV kg year)
Co-60 1.4 10-4 Bi-214 5.1 10-5 Tl-208 1.4
10-4
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Radioactive bg. (Phase-II)
K. Kroeninger, L. Pandola
800 M. Radon in water tank generated, not a issue.
Gerda Collab. , Jun 27-29, 2005
2) Gerda Background radioactive bg.
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Gerda Calibration Source
K. Kroeninger
Source inside container gt1k events in photon peak
in each segment
60Co, 22Na and 88Y, good candidates
Gerda Collab. , Jun 27-29, 2005
3) Gerda Calibration
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Summary Background Calibration
Top veto water Cerenkov veto of cosmic muon
?Phase-I prefers Top veto below penthouse (4.4
10-4 cnts/kg.y.keV) ?Phase-II Cerenkov veto
necessary (lt3 10-5) Cerenkov veto seems
efficient, more developement by A. Klimenko,
M. Bauer M. Knapp. Radioactive
background inside crystal, cable supports
?Sum 2 10-3, dominant Ge68 Co60 in crystal,
Ra226 in support ?expect pulse shape to help
further ?Ra contamination in water lt 2-3
10-4 Calibration source for Gerda ? Gerda
Note ready.
Gerda Collab. , Jun 27-29, 2005
2) Gerda Background Calibration
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3) RD H-M crystals LArGe
Simulation of existing Hd-Mo detectors
Comparison with measurement ? C. Tomei
(LNGS), O. Chkvorets (MPI-K) Simulating LArGe at
MPIK Gran Sasso (optical processes) ?
L. Pandola Compare LArGe simulation with
measurement (see TG1 summary) ? D. Franco
(MPI-K) Teststands at MPI Munich (see pulse
shape) ? K. Kroeninger
Many data verifications!
Gerda Collab. , Jun 27-29, 2005
3) RD
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Simulating Hd-Mo crystals
Det. 1 0.98 kg
old
new
ANG1
ANG3
ANG4
ANG2
1 m
new
C.Tomei
Gerda Collab. , Jun 27-29, 2005
3) RD
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Comparison with data Ba133
Performed by O. Chkvorets and S. Zhukov on
February 2005 inside the old LENS barrack first
and in LUNA 1 barrack afterwards. Detectors
shielded with 10 cm lead Radioactive sources
60Co and 133Ba (also 226Ra)
Gerda Collab. , Jun 27-29, 2005
3) RD
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Co60 comparison
General agreement with measurement. More to be
understood.
Ratio of gamma lines in data ? locate bg source
positions,
? verified by MC (O. Chkvorets in TG1)
Gerda Collab. , Jun 27-29, 2005
3) RD
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Simulating LArGe
L. Pandola
Simple setup
Goal complete simulation of the scintillation
photons
LAr scintillation large yield (40,000 ph/MeV)
but in the UV (128 nm)

• Surface reflection.
• Scattering absorption.
• Crystal shadowing effects.
• Properties of WLS.
• All depend on wave-lengths!

Gerda Collab. , Jun 27-29, 2005
3) RD
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It is complicated!!
Optical physics
Geant4 (and then MaGe) is able to produce track
optical photons (e.g. from scintillation or
Cerenkov)

• Processes into the game
• scintillation in LAr
• Cerenkov in LAr
• boundary and surface effects
• absorption in bulk materials
• Rayleigh scattering
• wavelenght shifting

Refraction index of LAr
Properties of all interfaces (reflectivity,
absorbance)
Absorption length of LAr
Rayleigh length of LAr
Emission spectrum of VM2000 (measured here) and QE
The optical properties of materials and of
surfaces (e.g. refraction index, absorption
length) must be implemented ? often unknown (or
poorly known) in UV
Gerda Collab. , Jun 27-29, 2005
3) RD
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Output from the simulation
Frequency spectrum of photons at the PM (to be
convoluted with QE!)
The ratio between the LAr peak and the optical
part depends on the WLS QE critical parameter
Scintillation yield ? 40,000 ph/MeV
Gerda Collab. , Jun 27-29, 2005
3) RD
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LArGe set-up at Gran Sasso
The geometry for the LArGe set-up at Gran Sasso
has been implemented in MaGe
It includes the shielding layers, the cryo-liquid
and the Ge crystals
Number of crystals columns and plans tunable by
macro (? interfaced with the general Gerda
geometry tools)
Available in MaGe and ready for physics studies
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MaGe progressphysics validation
D. Franco

• 2 data sets from
• 60Co source 168 g bare crystal in LN (stat
  5.2e10)
• 226Ra source with a 830 g conventional crystal
• 2 positions in the center (statistics 8.5e7)
  60mm away (statistics 4.0e8)
• LArGe-MPIK 60Co, 226Ra, 137Cs

• Three tests
• Comparison of the spectral shapes
• Efficiency ( of events in a gamma
  peak/disintegration)
• Ratio ( of events in a gamma peak/ of events in
  the gamma peak of reference)

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MaGe progressphysics validation Ra-226
calibration of conventional crystal
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Summary on LArGe Simulation
measurement
simulation
analysis presented in this talk is preliminary
Comparison limited by measurement. but we show
that LAr suppression works MaGe reproduces the
spectra fairly well
Gerda Collab. , Jun 27-29, 2005
3) RD
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4) MaGe verification with SHIELD
A. Denisov
SHIELD-HIT(INR RAS,KI,2001) (Energies at 1 TeV/A
are available)
SHIELDHI(INR RAS,1997) (Interactions of nucleons,
Pi, K, anti nucleons, muons, all (A,Z) nuclei.
All isotope and chemical compounds, complex
geometry)
SHIELD(INR RAS,1989) (Kernel had been totally
overwritten. Growth of functionality)
SHIELD(JINR,1972) (Nucleons-Pi mesons cascades
evolution up to energy 20 30 GeV )
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SHIELD is transparent
Improved CG module (Combinatorial geometry)
Geometry
LOENT (ABBN 28 constants)
Low energy neutrons transportation
MSDM generator (Multy Stage Dynamical
Model. Exclusive approach. )
Inelastic interactions
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MaGe
Energy transfer spectrum from muon to hadron
shower
Comparing with Bugaev - Bezrukov formula
SHIELD
MaGe
Simulation of simple geometry for hadron
transportation
Comparing results and analyzing discrepancies
Proposed comparison
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5) Pulse shape simulation analysis
Co60
Kevin Kroeninger
Gerda Collab. , Jun 27-29, 2005
5) Pulse Shape
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Pulse shape simulation

• How to simulate PS
• ? Calculate electric field E with given boundary
  bias voltage.
• Calculate weighting field for each segment
  (Ramos theory).
• ? Hits from MaGe.
• ? Convert hits into electron-hole pairs (1
  pair per 3eV).
• ? electric field ? Drift path.
• ? weighting field along path ? Induced
  charge in each segment.
• ? convolute with pre-amp DAQ effect.

Kevin Kroeninger
Gerda Collab. , Jun 27-29, 2005
5) Pulse shape
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Drifting field

• Example true coaxial n-type detector

Electrons
Holes
Electrons
Holes
Local energy deposition
Gerda Collab. , Jun 27-29, 2005
5) Pulse shape
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Weighting field

• Example true coaxial detector with 6 f- and 3
  z-segments

z 5.1 cm
z 7.7 cm
z 2.6 cm
IMPORTANT Particles do not move due
to weighting field
z
(Slices in z showing x-y plane)
y
Gerda Collab. , Jun 27-29, 2005
5) Pulse shape
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Pulse Shape simulated

• Full simulation of true coaxial 6-fold segmented
  detector

electrode
electrode
electrode

• Rising time
• R
• Left-right asymmetry
• ??

core
electrode
electrode
electrode
Charge
Time
Gerda Collab. , Jun 27-29, 2005
5) Pulse shape
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Rising time comparison
Risetime ns
Gerda Collab. , Jun 27-29, 2005
5) Pulse shape
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Pulse Shape analysis Mexico hat

• Examples of mexican hat filter for different
  widths

Distinguish power to some extent
Gerda Collab. , Jun 27-29, 2005
5) Pulse shape
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Summary on Pulse Shapes RD
Data-taking more ways of taking
single- multi-site events? PS simulation
first procedure established, describes
reasonably measurement (general
shapes, rising time etc). PS analysis
Mexico hat proof of principle.
All under developing!
We need your experience!!
Gerda Collab. , Jun 27-29, 2005
5) Pulse shape
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Summary of summary

• MaGe in good shape.
• Background under control, water cerenkov veto
  ongoing.
• Comparison with H-M crystal measurement helps
  understanding bg.
• LArGe simulation improved by measurement.
• Verification from other MC packages, FLUKA,
  SHIELD
• Pulse shape simulation analysis started.

Gerda Collab. , Jun 27-29, 2005
summary
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Group activity outlook

• LNGS L. Pandola, C. Tomei.
• Cerenkov veto, LArGe scintillation.
• MPI-K D. Franco, M. De Marco
• LArGe comparison with data.
• Tuebingen M. Bauer, M. Knapp Dubna A.
  Klimenko
• Cerenkov veto, neutron bg.
• MPI Munich K. Kroeninger, X. Liu
• Pulse shape, radioactive bg.
• Moscow A. Denisov, S. Belogurov
• SHIELD improving cross check MaGe
  (Geant4)

Your requests, suggestions contributions are
all welcome!
Gerda Collab. , Jun 27-29, 2005
Outlook
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Group Members
L. Pandola (Coordinator), C. Tomei (LNGS) M.
Bauer, M. Knapp (Tuebingen) D. Franco, M. De
Marco (MPI Heidelberg) K. Kroeninger, X. Liu
(MPI Munich) A. Klimenko (Dubna) A. Denisov,
S. Belogurov (Moscow)
Gerda Collab. , Jun 27-29, 2005