Background simulations: an update G. Luzón [email protected]@unizar.es S. Cebrián...

Background simulations: an updateBackground simulations: an update

G. Luzón [email protected]

S. Cebrián [email protected]

Paris, 14th February 2006

JRA1/N2 ILIAS Meeting

Outline:

General issues

Progress on simulation work:

• Neutron production by radioactivity

• Propagation of low energy neutrons

• Muon-induced neutrons

• Cosmogenic activation

Library of codes

mailto:[email protected]

mailto:[email protected]

Tasks for second and third years:

• Implementation of MC codes for the relevant backgrounds/instrumentation

• Optimisation of the codes

• Design and implementation of the library

• Analysis of data collected in the background monitoring campaign with MC codes

General issuesGeneral issues

S. Cebrián, JRA1/N2 ILIAS Meeting, Paris, 14 Feb 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


Meetings during last year:

• Informal meeting at Prague, 7 Feb 2005, at 2nd General ILIAS Meeting

• Meeting at Valencia, 12 Apr 2005, at N3-N6 Meeting

• Meeting at Zaragoza, 15 Sep 2005, after TAUP2005 Conference

Minutes and transparencies are available at N3 and JRA1 websites:

http://www.unizar.es/ilias/wp2Back/wp2BackSim.htm

http://bscw.pit.physik.uni-tuebingen.de:81/bscw/bscw.cgi

Next meeting:

• Informal meeting at Gran Sasso, at 3rd General ILIAS Meeting, 27 Feb – 3 Mar 2006.


http://www.unizar.es/ilias/wp2Back/wp2BackSim.htm

http://bscw.pit.physik.uni-tuebingen.de:81/bscw/bscw.cgi

Presentations at conferences during last year:

• Workshop on Exploring the Physics Frontier at the Deep Underground Laboratories (INT2005 –Seattle)

V.A. Kudryavtsev et al. Background Studies for Underground Particle Physics Experiments

• TAUP 2005 Workshop (Proceedings published in IoP).J. Puimedón et al. Neutrons from rock radioactivity in the new Canfranc underground LaboratoryJ. Ruz et al. Background shielding for the TPC of the CAST experimentR. Lemrani et al. Update of neutron studies in EDELWEISSS. Cebrián et al. Cosmogenic Cosmogenic activation activation in in germanium Double Beta Decay experimentsV.A. Kudryavtsev et al. Background studies for underground particle astrophysics experiments

New papers:• “Low energy neutron propagation in MCNPX and GEANT4”, R. Lemrani et al., to be published in NIMA [arXiv:hep-ex/0601030]


Neutron production from U/Th contaminationNeutron production from U/Th contamination

Useful codes:

• SOURCES gives neutron flux and energy spectrum: modified to include alphas with E>6.5 MeV

• Other codes used to estimate neutron yields do not provide neutron energy spectrumALPHN http://www.nea.fr/abs/html/ccc-0612.html J. Puimedón et al, TAUP2005


Progress of workProgress of work

Canfranc

http://www.nea.fr/abs/html/ccc-0612.html

http://www.nea.fr/abs/html/ccc-0612.html

Cross-sections added by VK in August 2003: 9- F-19 Vukolov et al.Vopr.At.Nauk.Ob.,4,31(1983)+extrap., vk 13/10/03 11-Na-23 E.B.Norman et al. Nucl. Phys. A390, 561 (1982), vk 19/08/03. 14-Si-28 C.W.Cheng et al. Can. J. Phys. 58, 697 (1980), vk, 19/08/03 17-Cl-35 A.J.Howard et al. ApJ, 188, 131 (1974), added by vk, 19/08/03 24-Cr-50 A.J.Morton et al. Nucl. Phys. A573, 276 (1994), vk 9/12/03 25-Mn-55 S.Sudar, S.M.Qaim. Phys. Rev. C, 50, 2408 (1994), vk 9/12/03 26-Fe-54 S.G.Tims et al. Nucl. Phys. A524, 479 (1991), vk 19/08/03 27-Co-59 R.H.Stelson et al. Phys. Rev. B, 133, 911 (1964), vk 19/08/03 28-Ni-60 R.H.Stelson et al. Phys. Re Rev. B, 133, 911 (1964), vk 19/08/03 28-Ni-60 R.H.Stelson et al. Phys. Rev. B, 133, 911 (1964), vk 9/12/03 28-Ni-62 J.L.Zyskind et al. Nucl. Phys. A331, 180 (1979), vk 9/12/03 28-Ni-64 J.L.Zyskind et al. Nucl. Phys. A331, 180 (1979), vk 9/12/03 29-Cu-63 R.H.Stelson et al. Phys. Rev. B, 133, 911 (1964), vk 19/08/03 29-Cu-65 R.H.Stelson et al. Phys. Rev. B, 133, 911 (1964), vk 19/08/03 7- N-14 W. Gruhle et al. Nucl. Phys. A 186 (1972) 257, vk 11/03/04

• Updated library of new SOURCES cross sections at code repository


(,n) cross sections updated and added in SOURCES• Using recent experimental results: Na• Making calculations if there is no measurement: 35Cl, Fe, Cu, Ca, TiGNASH-FKK (http://www.nea.fr/abs/html/psr-0125.html)EMPIRE (http://www.nndc.bnl.gov/empire219) Ca, Mg

Cross-sections added by Rachid Lemrani - July 2005 (calculations with empire-2.19): 12-Mg-24 - new 12-Mg-25 - update 12-Mg-26 - update 14-Si-29 - update 14-Si-30 - update 15- P-31 - update 19- K-39 - new 19- K-40 - new 19- K-41 - new 20-Ca-42 - C.W.Cheng et al Jour. of Physics, Part G (Nucl.and Part.Phys.) 5(1979)1261 20-Ca-43 - new 20-Ca-44 - new 20-Ca-46 - new 20-Ca-48 - new 22-Ti-46 - new 22-Ti-47 - new 22-Ti-48 - new 22-Ti-49 - new 22-Ti-50 - new

R. Lemrani et al., to be published in NIMA [arXiv:hep-ex/0601030].

Similar production rates found for Modane and Boulby rock (1.3 n/g/y and 1.5 n/g/y) despite higher radioactivity levels in Modane: lower (,n) reaction thresholds in NaCl


Propagation of low energy neutronsPropagation of low energy neutrons

Neutron propagation of low energy neutrons through rock, lead and hydrocarbon moderator has been compared for GEANT4, GEANT3 and MCNPX using the same neutron inputs and geometry benchmark



Propagation through rock: neutron spectra from SOURCES at rock boundary

NaCl Modane

Maximum differences between codes ~15-20%

GEANT4 inelastic cross sections on Cl corrected

Smaller neutron flux in Modane due to water content in rock

Flux enhancement (50%, 30%) due to backscattering of neutrons when considering real caverns



Propagation through shieldings: neutron energy spectra after various shielding thicknesses (NaCl rock)

0 to 50 g/cm2 CH2 30 cm Pb+ 0 to 40 g/cm2 CH2

Reasonable agreement between GEANT4-MCNPX: maximum differences after 50 g/cm2 of CH2, with MCNPX flux ~50% higher than in GEANT4



Neutron flux as a function of CH2 thickness (NaCl rock)

~55 g/cm2 should suppress low energy neutron flux from environment by more than 6 orders of magnitude

Summarizing…

Good agreement between GEANT4 and MCNPX for propagation of low energy neutrons:

• after correction of bug in inelastic cross sections for Cl in GEANT4 library

• main conclusions do not depend on code



Neutron production + Propagation through rock and Neutron production + Propagation through rock and scintillator:scintillator: comparison of simulations and measurements

• SOURCES for neutron production and MCNPX for propagation

• Measurement at Modane

R. Lemrani et al., TAUP2005

Shape well described but differences of a factor ~2 in normalization

SOURCES produces softer neutron energy spectrum than other calculations: transitions to excited states in SOURCES (probabilities based on calculations) may produce lower energy transfers to neutrons


Production of neutrons by muonsProduction of neutrons by muons

Comparison between GEANT4 and FLUKA was made: yields, energy spectrum, lateral distribution, dependance on material

See H. M. Araujo et al., Nucl.Instrum.Meth. A545 (2005) 398-411; M. Bauer et al., Proc. IDM2004, p. 494; M. Horn, Valencia meeting April 2005; M. Bauer, Valencia meeting April 2005.

• Agreement between them within a factor ~2 (even better for some materials and energies), although FLUKA prediction is always higher

• Bertini and Binary GEANT4 models agree within ~20%

Pending problem: some experimental results disagree with GEANT4/FLUKA predictions, being the measured neutron production significantly higher than in calculations

• Problem forwarded to GEANT4 collaboration

• Data from experiments (LVD, SNO, KamLAND, Borexino CTF) would be welcome to check neutron production by muons

• Dedicated experiment to measure neutron flux induced by muons in lead?


Other non-ILIAS results:

1. FLUKA validation: calculation of production of 12B and 16N in oil- and water-based detectors by (n,p) reactions produced by muon-induced neutrons found to be good agreement with measurements from KamLAND

C. Galbiati, J. F. Beacom, Phys. Rev. C 72 (2005) 025807


2. FLUKA correction?: neutron multiplicity modified in muon-induced cascades, increasing neutron yields, despite energy imbalance

D. M. Mei and A. Hime, [arXiv:astro-ph/0512125]

• Procedures and conclusions in this work very controversial: see postings at the MonteCarlo mailing list

http://webmail.unizar.es/pipermail/montecarlo/2005-December/000046.html

2. Analysis of computational codes for n/p activation: Monte Carlo or semiempirical codes

Detailed report at http://idea.dipscfm.uninsubria.it/frontend/docs/reports/cosmogenics-task2.pdf

Cosmogenic activation of materialsCosmogenic activation of materials1. Collection of available data on production cross sections:

Detailed report at http://idea.dipscfm.uninsubria.it/frontend/docs/reports/cosmogenics-task1.pdf

Searching for p/n activation cross-sections on targets of interest (Ge, Te) on the literature and from nuclear data libraries

Collecting information on: • Target materials and product isotopes covered• Projectiles allowed• Range of applicable energies• Physical models included and/or experimental data sets considered for cross-sections • Checks with experimental data• “Technical” information: language, code source, support, ...


• Activation targets: Te, Ge, Cu• Similar methodology:

i. To try to find the most reliable evaluation of the excitation functions by nucleons of relevant long-lived products, taking into account all available experimental data and calculations

ii. To evaluate production rates at sea level considering a particular cosmic ray spectrum

iii. To quantify deviations between experimental data and calculations (for both cross sections and production rates, if possible)

3. Study of particular activation problems, comparing calculations with experimental data when possible


To identify the most reliable codes and the weak points of computations for treating our problems

Excitation function by nucleons of 68Ge in natural Ge


S. Cebrián et al, TAUP2005

Production rates (kg-1d-1) in Cu estimated and compared with other results

COSMO F&M '04Heusser'05

(at LNGS)

972,3 19,9±2,6

30,5 155±35

131,5 142,6±7,8

25,7 2675,5 181±16

134,2 52,2 18,6±1,8

39±10

4,6±1,6

at LNGS

48,1

185,5

335,1

204,5

68,3

13,6

8,0

LE ME HE 56Co 2,6 + 18,0 + 2,3 22,957Co 29,7 + 55,8 + 2,8 88,358Co 90,4 + 65,7 + 3,5 159,660Co 81,8 + 14,2 + 1,4 97,454Mn 3,6 + 25,9 + 3 32,559Fe 4,3 + 1,9 + 0,3 6,546Sc 0 + 2,5 + 1,3 3,8

x 2.1

Modified COSMO: L. Baudis, R. W. Schnee, NUSL White Paper, 2002

J. A. Formaggio, C. J. Martoff, Annu. Rev. Nucl. Part. Sci. 54 (2004) 361

G. Heusser, LRT2004, Sudbury, December 2004. G. Heusser, M. Laubenstein, H. Neder, to appear in “Radionuclides in the Aquatic environment” (Ed. Povinec) Elsevier, 2005


Global analysis of all the activation studies is underway to conclude about improvements in the considered codes

Report (second year deliverable in JRA2) will be available soon

Some preliminary conclusions:

• In GEANT4, at medium-high energies, the model which gives clearly the best results is Bertini cascade

• Concerning semiempirical codes, YIELDX based on the most updated version of the formulas, should be used

• Deviations factors F between available measured production cross sections and different calculations have been evaluated: range from ~1.5 to ~2.5


Some preliminary conclusions:

• Since:

1. production cross sections by neutrons and protons at low energies (<200 MeV) are significantly different in most cases

2. proton flux at low energy is negligible at sea level

the following way of evaluating the excitation functions is proposed:

at low enegy, cross sections specifically calculated for neutrons (MENDL library, HMS-ALICE)

at medium-high energies, semiempirical YIELDX calculations


• Comparisons of estimated production rates using this recipe with measurements in Ge and Cu are good for some products, deviations up to factor 3 in many cases

Further refinements in cross sections at medium energies could be necessary

• Web-site: http://www.unizar.es/ilias/wp2Back/wp2BackSim.htm

(most of the information also available at N3 website)

• FTP repository: http://www.unizar.es/ilias/JRA1/09.htm

under password, ask account at [email protected], [email protected]

General information about codes, links to code web-sites, access to some codes.

Modifications to codes:

• Updated version of SOURCES with new cross sections

• Interface between GEANT4 and SOURCES4A

• Interface between MUSUN and GEANT4 Examples

Repositories:


Library of codesLibrary of codes

GEANT4

• Contact has been established between the GEANT4 Collaboration and the undeground physics community in ILIAS

– Main requirements coming from the underground physics community forwarded to GEANT4

– Good will to fulfill them, consistently with the available manpower

• Production of -induced neutrons in high-Z materials

• Propagation of Low Energy neutrons

• Inelastic scattering of neutrons

• Interactions of high-energy muons

• Isotope production


– To go further than just the user feedback to solve bugs and small problems … which on the other hand is very important!

• Problem with inelastic cross sections for neutrons on Cl solved

• Patch available by Luciano Pandola for bug for simulation of de-excitation gammas in inelastic process Ge(n,n’)Ge*

• Bug found on inelastic cross sections of 62Ni for (n,p) in 62Cu

solved in new G4NDL3.8 !


• GEANT4 validation efforts

- Geant4 ElectroMagnetic physics models (“standard” and “low energy”) are being validated in a systematic and quantitative way

• GEANT4 validation efforts

- Geant4 ElectroMagnetic physics models (“standard” and “low energy”) are being validated in a systematic and quantitative way

- A similar systematic effort has not been performed yet for hadronic physics, but it is ongoing for example for isotope production: reliability and limits of Bertini and Binary cascade models being clarified


Summary and OutlookSummary and Outlook

Very active collaboration in background simulations and cross-checks between ILIAS participants in different fields of interest:

This common work is giving rise to code improvements: interfaces between complementary codes, updates of cross sections, communication with GEANT4 Collaboration

Further work is pending for validation of codes against background measurements in underground labs


• low energy neutron propagation: GEANT4 and MCNPX proved to be compatible• muon-induced neutrons: GEANT4 and FLUKA compatible within ~2, but some disagreements with data still to be clarified

• cosmogenic activation: conclusions on analyzed codes to be delivered

• neutron production from radioactivity: upgraded SOURCES seems to be the best option

27Al42Ca 48Ti

23Na18O

EMPIRE-II Control Plots: accuracy ~20%

R. Lemnrani, ILIAS Common Meeting on MC simulations, Zaragoza, 15 Sept 2005S. Cebrián, JRA1/N2 ILIAS Meeting, Paris, 14 Feb 2006

Background simulations: an update G. Luzón [email protected]@unizar.es S. Cebrián...

Documents

Transcript of Background simulations: an update G. Luzón [email protected]@unizar.es S. Cebrián...