Summary TG-10 MC & Background Xiang Liu for TG-10

Generator, physics processes, material, management, etc. Last Collab. Meeting Generator, physics processes, material, management, etc. mjgeometry mjio gerdaio gerdageometry 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. Quick remind of what happened last collaboration meeting. Gerda Collab. , Jun 27-29, 2005 Last Collaboration meeting

Outline Achievement since then: MaGe update Gerda related: Background & Calibration sources R&D related: H-M crystals, LArGe Verification (Comparison) with SHIELD Analysis: Pulse shape simulation & analysis Summary & Outlook Mention that, while number 2 is still “Letter of Intent” style, that is, to produce some numbers for the Gerda proposal, the rest parts are about different programs, namely, R&D simulation, further detailed comparison and verification of MaGe, and the analysis of pulse shapes. People talked about it a lot, now we really started, and finally! Gerda Collab. , Jun 27-29, 2005 outline

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. Second message that I want to deliver, namely Gerda ready for people to use. Gerda Collab. , Jun 27-29, 2005 1) Further MaGe development

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 First physics topic, about Gerda proposal, try to finish the background analysis for Gerda. Presentations concerning muon or muon-induced background were already presented yesterday at the plenary session, simulation for transportation shielding was mentioned in TG2. Radioactive background are almost finished now. radioactive calibration Gerda Collab. , Jun 27-29, 2005 2) Gerda Background

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: 3.1 ·10-5 Bi-214: 1.3 ·10-5 Tl-208: 7.5 ·10-5 Co-60: 1.6 ·10-5 Bi-214: 1.2 ·10-5 Tl-208: 5.8 ·10-5 Using our limits for Cu, PTFE and Si Rate in roi: <1.5·10-3 / (keV kg year) Background estimations in the support for phase I estimated, Stefan schoenet presented the simulation results, which satisfied our request for Phase-I. Co-60: 1.4 ·10-4 Bi-214: 5.1 ·10-5 Tl-208: 1.4 ·10-4

Bkg. Index [10-3 cnts/kg/keV/y] Radioactive bg. (Phase-II) K. Kroeninger, L. Pandola Source Activity Suppr. Factor Bkg. Index [10-3 cnts/kg/keV/y] 60Co (holder) ? (0.7 – 2.4)·10-5 208Tl (holder) 9 μBq/kg 1.2 ·10-4 0.3 214Bi (holder) 25 μBq/kg 2.5 ·10-5 0.2 68Ge (crystal) 58 /kg/year 2.2 ·10-4 0.8 208Tl (surface) 80 /surface/year 0.03 210Pb (surface) 1 μBq/surface 0.6 ·10-5 0.04 60Co (cyrstal) 15 /kg/year 4.7 ·10-5 0.07 226Ra (cable) < 26 μBq/kg <1 2νββ T1/2 = 1.74·1021 y < 10-6 < 0.45 Background for Phase-II almost satisfies our request as well. We located the major background contributions. 800 M. Radon in water tank generated, not a issue. Gerda Collab. , Jun 27-29, 2005 2) Gerda Background – radioactive bg.

Gerda Calibration Source K. Kroeninger Nothing more to say. Source inside container >1k events in photon peak in each segment 60Co, 22Na and 88Y, good candidates Gerda Collab. , Jun 27-29, 2005 3) Gerda Calibration

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 (<3 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 < 2-3 10-4 Calibration source for Gerda  Gerda Note ready. Gerda Collab. , Jun 27-29, 2005 2) Gerda Background & Calibration

3) R&D: 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) R&D

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) R&D

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) R&D

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) R&D

Simulating LArGe L. Pandola Simple setup: Goal: complete simulation of the scintillation photons PMT crystal reflector and WLS tank 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) R&D

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) R&D

Output from the simulation Ar peak VM2000 emission Cerenkov spectrum 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) R&D

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

MaGe progress: physics 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)

MaGe progress: physics validation Ra-226 calibration of conventional crystal

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) R&D

SHIELD-HIT(INR RAS,KI,2001) 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 )

SHIELD is transparent Improved CG module (Combinatorial geometry) LOENT (ABBN 28 constants) Low energy neutrons transportation MSDM generator (Multy Stage Dynamical Model. Exclusive approach. ) Inelastic interactions

Comparing with Bugaev - Bezrukov MaGe Energy transfer spectrum from muon to hadron shower Comparing with Bugaev - Bezrukov formula MaGe SHIELD Simulation of simple geometry for hadron transportation Comparing results and analyzing discrepancies Proposed comparison

5) Pulse shape simulation & analysis Co60 Kevin Kroeninger Gerda Collab. , Jun 27-29, 2005 5) Pulse Shape

Pulse shape simulation How to simulate PS:  Calculate electric field E with given boundary & bias voltage. Calculate “weighting field” for each segment (Ramo’s 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 Explain hits: energy deposit in sensitive volume. Gerda Collab. , Jun 27-29, 2005 5) Pulse shape

Drifting field Example: true coaxial n-type detector Electrons Holes Local energy deposition Holes Gerda Collab. , Jun 27-29, 2005 5) Pulse shape

Weighting field Example: true coaxial detector with 6 φ- and 3 z-segments z = 2.6 cm z = 5.1 cm z = 7.7 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

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

Rising time comparison Risetime [ns] Gerda Collab. , Jun 27-29, 2005 5) Pulse shape

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

We need your experience!! Summary on Pulse Shapes “R&D” 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

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

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

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