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Physics of Massive Neutrinos 2007 Joint Annual Meeting of N4-IDEA and N6/WP1 ENTApP

Cosmogenic induced activity. Task coordinators: Maura Pavan, Università di Milano-Bicocca (Italy) Susana Cebrián, Universidad de Zaragoza (Spain). OUTLINE Motivation of the task Simulation-based work Irradiation tests. Physics of Massive Neutrinos 2007

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Physics of Massive Neutrinos 2007 Joint Annual Meeting of N4-IDEA and N6/WP1 ENTApP

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  1. Cosmogenic induced activity Task coordinators: Maura Pavan, Università di Milano-Bicocca (Italy) Susana Cebrián, Universidad de Zaragoza (Spain) • OUTLINE • Motivation of the task • Simulation-based work • Irradiation tests Physics of Massive Neutrinos 2007 Joint Annual Meeting of N4-IDEA and N6/WP1 ENTApP Blaubeuren, 1st-5th July 2007

  2. The problem of cosmogenic activity in DBD • Production of long-lived radioactive isotopes in set-up materials due to cosmic rays at sea level can become a serious hazard for experiments looking for rare events, like DBD projects • Production rates R of induced isotopes depend on: • production cross sectionss • spectrum of cosmic rays f • Activities A induced on a material depend also on: • exposure and decay history S. Cebrián, Cosmogenic Induced Activity PMN2007, IDEA meeting, Blaubeuren, July 2007

  3. Cosmogenic activation studies in DBD before IDEA Cosmogenic activation studies for DBD promoted by IDEA within ILIAS S. Cebrián, Cosmogenic Induced Activity PMN2007, IDEA meeting, Blaubeuren, July 2007

  4. WP4 in IDEA • “Cosmogenic induced activity” is the Work Package 4 of JRA2 (IDEA) in ILIAS, in connection with Task 4 (R&D on radiopurity of materials and purification techniques) of JRA1 (Low background techniques for deep underground science) • Task Objectives: • Participants: Heidelberg / Milano / Zaragoza S. Cebrián, Cosmogenic Induced Activity PMN2007, IDEA meeting, Blaubeuren, July 2007

  5. Simulation-based work GOAL: Identification of the most reliable codes and of the weak points of computations for treating our problems in order to improve them Studies for relevant activation problems in DBD using different codes and comparing with data when possible DELIVERABLE: upgrades in codes + answers to open questions about activation problems in DBD related technical report http://idea.dipscfm.uninsubria.it/frontend/docs/reports/report_upgrade_codes.pdf S. Cebrián, Cosmogenic Induced Activity PMN2007, IDEA meeting, Blaubeuren, July 2007

  6. Description of activation studies • Te, Ge, and Cu chosen as targets of activation, due to their relevance in DBD experiments • Evaluation of cosmogenic activation yields of relevant long-lived products in each of these three targets by nucleons at sea level following a common methodology: • To collect available information on isotope production cross sections, from measurements and from calculations (new or from libraries) • To choose the best description of the excitation functions of products (calculating deviation factors between measurements and different calculations) • To estimate the production rates of relevant products considering a particular cosmic ray spectrum and to compare them with previous estimates and/or measurements S. Cebrián, Cosmogenic Induced Activity PMN2007, IDEA meeting, Blaubeuren, July 2007

  7. E>20 MeV: • 4.5 10-3 n/cm2/s Cosmic neutron spectrum:parameterization based on measurements • J. F. Ziegler, IBMJournal of Research and Development 42 (1998) 1. S. Cebrián, Cosmogenic Induced Activity PMN2007, IDEA meeting, Blaubeuren, July 2007

  8. Description of activation studies • Te, Ge, and Cu chosen as targets of activation, due to their relevance in DBD experiments • Evaluation of cosmogenic activation yields of relevant long-lived products in each of these three targets by nucleons at sea level following a common methodology: • To collect available information on isotope production cross sections, from measurements and from calculations (new or from libraries) • To choose the best description of the excitation functions of products (calculating deviation factors between measurements and different calculations) • To estimate the production rates of relevant products considering a particular cosmic ray spectrum and to compare them with previous estimates and/or measurements • Simulation of some irradiation experiments with beams using both the semiempirical code YIELDX and the Monte Carlo package GEANT4 • Global analysis of all activation studies (comparing calculations and simulations with all available experimental information) to conclude on codes S. Cebrián, Cosmogenic Induced Activity PMN2007, IDEA meeting, Blaubeuren, July 2007

  9. General conclusions on codes (I) From simulation of irradiation experiments… • At high energies, in GEANT4 the Bertini model gives the best agreement with measurements • At low energies (<100 MeV), in GEANT4 the precompound model underestimates yields in Ge in a factor 3 at least • Semiempirical YIELDX reproduces well high energy data S. Cebrián, Cosmogenic Induced Activity PMN2007, IDEA meeting, Blaubeuren, July 2007

  10. General conclusions on codes (II) From excitation functions … • Use of YIELDX is preferred rather than COSMO, since experimental results on Te targets have solved the problem of some found discrepancies between them • Deviation factors F (averaged on energy and/or products) evaluated for different calculations range from ~1.5 to ~2.5 HMS-ALICE gives best agreement at low energies YIELDX predictions, very good at high energies, worsen in the medium energy range S. Cebrián, Cosmogenic Induced Activity PMN2007, IDEA meeting, Blaubeuren, July 2007

  11. Differences on production cross sections by neutrons or protons are not negligible at low energies for many cases (corroborated by available measurements) important to properly estimate activation yields by neutrons General conclusions on codes (III) From excitation functions … • Proposed recipe for evaluation of excitation functions: • at low energies, calculations specifically developed for neutrons can be used from MENDL or using HMS-ALICE. • at medium and high energies, YIELDX calculations, assuming cross sections by neutrons and by protons similar enough Biggest uncertainties from the medium energy range, where there is no neutron measurement to validate calculations S. Cebrián, Cosmogenic Induced Activity PMN2007, IDEA meeting, Blaubeuren, July 2007

  12. Upgrades in codes (I) Semiempirical codes • YIELDX only can calculate the production cross section of a product in a target nucleus at a fixed energy, while COSMO derives activities for selected exposure and decay times, assuming a certain cosmic ray flux. • People from University of Warwick is working on producing an up-to-date C++ version of the COSMO code • benchmarking the code against results collected within IDEA • plan to release the code during 2007 S. Cebrián, Cosmogenic Induced Activity PMN2007, IDEA meeting, Blaubeuren, July 2007

  13. Upgrades in codes (II) Monte Carlo codes: GEANT4 • Contact has been established between GEANT4 Collaboration and ILIAS community working on simulations • special ILIAS contributions at next 12th GEANT4 Collaboration Workshop, 13-19 September 2007, UK • Great efforts for systematic validation of hadronic models ongoing within GEANT4 collaboration with the aim “to find or develop the best models in each kinematic range or use case. It is unrealistic to try to develop one super-model” GEANT4 Review, CERN, 16-20 April 2007 “GEANT4 Hadronics Overview”, A. Heikkinen “Hadronic Physics Validation”, D. Wright http://indico.cern.ch/conferenceDisplay.py?confId=14946 • extensive comparison with neutron production data (100 MeV-3 GeV) and measured (p,nX) cross sections (25-120 MeV) • LEP, Binary cascade, Bertini cascade models S. Cebrián, Cosmogenic Induced Activity PMN2007, IDEA meeting, Blaubeuren, July 2007

  14. GEANT4 Review, CERN, 16-20 April 2007, “Hadronic Physics Validation”, D. Wright http://indico.cern.ch/conferenceDisplay.py?confId=14946 S. Cebrián, Cosmogenic Induced Activity PMN2007, IDEA meeting, Blaubeuren, July 2007

  15. Upgrades in codes (II) Monte Carlo codes: GEANT4 • Contact has been established between GEANT4 Collaboration and ILIAS community working on simulations • Great efforts for systematic validation of hadronic models ongoing within GEANT4 collaboration with the aim “to find or develop the best models in each kinematic range or use case. It is unrealistic to try to develop one super-model” GEANT4 Review, CERN, 16-20 April 2007 “GEANT4 Hadronics Overview”, A. Heikkinen “Hadronic Physics Validation”, D. Wright http://indico.cern.ch/conferenceDisplay.py?confId=14946 • New models, some with good isotope production properties, are being incorporated in GEANT4 S. Cebrián, Cosmogenic Induced Activity PMN2007, IDEA meeting, Blaubeuren, July 2007

  16. GEANT4 Review, CERN, 16-20 April 2007, “Hadronic Physics Validation”, D. Wright http://indico.cern.ch/conferenceDisplay.py?confId=14946 S. Cebrián, Cosmogenic Induced Activity PMN2007, IDEA meeting, Blaubeuren, July 2007

  17. GEANT4 Review, CERN, 16-20 April 2007, “GEANT4 Hadronics Overview”, A. Heikkinen http://indico.cern.ch/conferenceDisplay.py?confId=14946 S. Cebrián, Cosmogenic Induced Activity PMN2007, IDEA meeting, Blaubeuren, July 2007

  18. GEANT4 Review, CERN, 16-20 April 2007, “Hadronic Physics Validation”, D. Wright http://indico.cern.ch/conferenceDisplay.py?confId=14946 S. Cebrián, Cosmogenic Induced Activity PMN2007, IDEA meeting, Blaubeuren, July 2007

  19. Upgrades in codes (II) Monte Carlo codes: GEANT4 • Contact has been established between GEANT4 Collaboration and ILIAS community working on simulations • Great efforts for systematic validation of hadronic models ongoing within GEANT4 collaboration with the aim “to find or develop the best models in each kinematic range or use case. It is unrealistic to try to develop one super-model” GEANT4 Review, CERN, 16-20 April 2007 “GEANT4 Hadronics Overview”, A. Heikkinen “Hadronic Physics Validation”, D. Wright http://indico.cern.ch/conferenceDisplay.py?confId=14946 • New models, some with good isotope production properties, are being incorporated in GEANT4 The isotope production capabilities in GEANT4 are expected to be improved S. Cebrián, Cosmogenic Induced Activity PMN2007, IDEA meeting, Blaubeuren, July 2007

  20. Irradiation tests GOAL: to measure the production cross-sections or the rates of production with n/p beams on the targets of interest in dedicated experiments Essential to validate and refine calculations with codes Irradiation experiments in Teand Cuhave been already carried out and others are underway S. Cebrián, Cosmogenic Induced Activity PMN2007, IDEA meeting, Blaubeuren, July 2007

  21. Experiment on Te • Initial problem COSMO predicted a high production cross section of 60Co in Te between 1-3 GeV Disagreement with YIELDX calculations and measurement for 1.85 GeV p at Berkeley (Bardayan’97) 60Co production in nat Te Irradiation experiment proposed and already carried out at CERN with 1.4 GeV p S. Cebrián, Cosmogenic Induced Activity PMN2007, IDEA meeting, Blaubeuren, July 2007

  22. Features of experiment • Results • Activation yields of many different products identified (Rb, Rh, Sn, In, Sb isotopes) and compared with YIELDX calculations • 60Co production cross sections (mb): Sensitivity of CUORE to 130Te DBD is not jeopardized by cosmogenic 60Co in crystals and YIELDX calculations in good agreement with measurements S. Cebrián, Cosmogenic Induced Activity PMN2007, IDEA meeting, Blaubeuren, July 2007

  23. Now, the highest energies available in measured production cross sections (p,X) in Ge are 660-800 MeV This experiment will be very useful to validate high energy calculations. Plans for Ge irradiation with protons • Beam irradiation experiment scheduled • By Milano group together with American collaborators • Ge samples • Proton beams with energies 1.4 and 24 GeV • At CERN S. Cebrián, Cosmogenic Induced Activity PMN2007, IDEA meeting, Blaubeuren, July 2007

  24. Experiment on Cu • Natural irradiation experiment • By Modane group in JRA1 • Sample: brick of Cu of 2250 g • More than 3 months of exposure to cosmic rays at ~2000 m in Modane • Gamma counting with HPGe detector underground just after irradiation Result: production rate of 60CoR < 5 mBq/kg S. Cebrián, Cosmogenic Induced Activity PMN2007, IDEA meeting, Blaubeuren, July 2007

  25. Plans for NaI • Natural irradiation experiment underway • By University of Zaragoza group, in connection with the ANAIS experiment intended to investigate the WIMP annual modulation effect • One NaI crystal with a mass of 10.7 kg exposed to cosmic rays at sea level during several years and other crystals during much shorter periods of time S. Cebrián, Cosmogenic Induced Activity PMN2007, IDEA meeting, Blaubeuren, July 2007

  26. Estimate of the expected yield of some relevant long-lived products • excitation functions selected after analyzing available experimental data on cross sections: MENDL libraries and YIELDX calculations. • cosmic ray spectrum at sea level from Ziegler parametrization. • A background measurement with exposed crystals can be made in the Canfranc Underground Laboratory to check these predictions S. Cebrián, Cosmogenic Induced Activity PMN2007, IDEA meeting, Blaubeuren, July 2007

  27. Outlook S. Cebrián, Cosmogenic Induced Activity PMN2007, IDEA meeting, Blaubeuren, July 2007

  28. Outlook: ILIAS-NEXT JRA5: “Supporting simulations and data analysis for underground physics” WP1 Background from radioactivity. WP2 Background induced by cosmic rays. WP3 Modelling detectors and physics processes. Task 2.1 Background from cosmic rays at surface Task 2.2 Background from muon-induced neutrons underground • DELIVERABLES: • Report on the activation rates of different materials due to cosmic rays in the atmosphere and underground • Report on the muon-induced background in detectors for neutrino mass measurements and methods for its suppression • List of recommendations for producing, storing and using materials exposed to cosmic rays, in underground experiments S. Cebrián, Cosmogenic Induced Activity PMN2007, IDEA meeting, Blaubeuren, July 2007

  29. Summary • Activation studies have been carried out for Te, Ge and Cu, obtaining some general conclusions regarding the use of different computational codes for cosmogenic activation in DBD experiments • Validation and improvement of isotope production capabilities in GEANT4 are ongoing • Different irradiation experiments on Te and Cuhave been performed while others on Ge and NaI are underway, some of them in collaboration with people from JRA1 in ILIAS S. Cebrián, Cosmogenic Induced Activity PMN2007, IDEA meeting, Blaubeuren, July 2007

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