Cosmogenic induced activity Susana Cebrián [email protected]@unizar.es University of Zaragoza (Spain) IDEA (Integrated Double-beta decay European

Cosmogenic induced activityCosmogenic induced activity

Susana Cebrián [email protected]

University of Zaragoza (Spain)

IDEA (Integrated Double-beta decay European Activities)

Prague, 20th-21st April 2006

Task coordinators: Maura Pavan, Susana Cebrián

mailto:[email protected]

Implementation plan

Outline of the talk

• Simulation-based work and related report

• Irradiations tests

• Outlook and summary

S. Cebrián, Cosmogenic Induced Activity IDEA meeting, Prague, April 2006

WP Task

9.R2 - Table 1 – IDEA - Second 18 months Execution Plan

13st to 18th month (1.04.2005-30.09.2005)

19th to 24th month(1.10.2005-31.03.2006)

25th to 30th month(1.04.2006-30.09.2006)

4 B1

Tasks

- Up-grade and development of simulation codes

- Upgrading of existing codes for n/p activation- Design of further n/p activation tests on Ge and TeO2

- further n/p activation experiments

- Start-up of tests at CERN and other labs on Ge and TeO2

Milestones and Delivera

bles

- Upgraded codes for n/p activation and related technical report

- progress report

COLLABORATION WITH JRA1 (WP4 “Radiopurity of materials”):

Shared interest in the cosmogenic activation of other targets like Cu and NaI

S. Cebrián, Cosmogenic Induced Activity

PROCEEDINGS:

• "Cosmogenic activation of materials"J. Amaré, B. Beltrán, S. Capelli, F. Capozzi, J. M. Carmona, S. Cebrián, O. Cremonesi, E. Garcia, I.G. Irastorza, H. Gómez, G. Luzón, M. Martínez, J. Morales, A. Ortiz de Solorzano, M. Pavan, C. Pobes, J. Puimedon, A. Rodríguez, J. Ruz, M.L. Sarsa, L. Torres, J. A. VillarAIP (American Institute of Physics) Conference Proceedings (Proceedings of the Workshop on Low Radioactive Techniques 2004, Sudbury, Canada, December 2004) Vol. 785 p. 267-271 (September 2005).

• "Cosmogenic activation in germanium double beta decay experiments"S. Cebrián, J. Amaré, B. Beltrán, J. M. Carmona, E. Garcia, I.G. Irastorza, H. Gómez, G. Luzón, M. Martínez, J. Morales, A. Ortiz de Solorzano, C. Pobes, J. Puimedon, A. Rodríguez, J. Ruz, M.L. Sarsa, L. Torres, J. A. VillarTo appear in Journal of Physics: Conference Series, IoP, (Proceedings of the TAUP2005 Conference, Zaragoza, Spain, September 2005).

General issues

IDEA meeting, Prague, April 2006


Simulation-based workGOAL: 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: Te, Ge, Cu

In the first two years…

DELIVERABLE: upgrades in codes and related technical report

http://idea.dipscfm.uninsubria.it/frontend/docs/reports/report_upgrade_codes.pdf

+ answers to open questions about activation problems in DBD


• Remind of activation studies

• General conclusions on codes

• Upgrades in codes

http://idea.dipscfm.uninsubria.it/frontend/docs/reports/report_upgrade_codes.pdf


Description of activation studies (I)

• 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:

1. To collect available information on isotope production cross

sections, from measurements and from calculations (new or from

libraries)2. To choose the best description of the excitation functions of products

(calculating deviation factors between measurements and different

calculations)

3. To estimate the production rates of relevant products considering a

particular cosmic ray spectrum and to compare them with previous

estimates and/or measurements


J. F. Ziegler, IBM Journal of Research and Development 42 (1998) 1.

E>20 MeV:4.5 10-3 n/cm2/s

Cosmic neutron spectrum: parameterization based on measurements

)()( EEdER n

dectt eeRA )1( exp



Description of activation studies (II)

• Simulation of some irradiation experiments with beams using both the

semiempirical code YIELDX and the Monte Carlo package GEANT4

Details of all these activation studies presented at IDEA meetings:

Heidelberg: Te

Paris: Ge

Zaragoza: Cu

and summarized in the delivered report

• Global analysis of all activation studies (comparing calculations and

simulations with all available experimental information) to conclude on codes


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

Deviation factors

Bertini cascade

Binary cascade

Te, ~1.8 GeV

Ge, 660 MeV

~2

3.2

>10

5.9

Semiempirical YIELDX reproduces well high energy data

YIELDX

~3

1.9


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

Deviation factors (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


General conclusions on codes (III)

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

From excitation functions …

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 (IV)

From production rates …

Most of the cosmogenic yield is usually due to neutrons of some hundreds

of MeV. However, for some particular products with small A, like 68Ge in

natural Ge and 60Co in Cu, most of the yield seems to come from neutrons

below 100 MeV.

The use of only semiempirical codes to obtain cross sections can

introduce significant deviations for production rates since their applicability at

low energies is very limited

Our estimates of production rates overestimate in a factor 2-3 rates

deduced experimentally in Ge; better agreement is achieved for some

nuclides in Cu, although maximum discrepancies in this case are also

around a factor 3.

A factor of ~3 of uncertainty should be considered when using our recipe

Further refinements in cross sections at medium energies could be necessary


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.

A code is being prepared to compute directly also activities based on the YIELDX routine.

Monte Carlo codes: GEANT4

Contact has been established between GEANT4 Collaboration and ILIAS

community working on simulations


Upgrades in codes (II)


“Validation of GEANT4 Bertini Cascade nuclide production using parallel ROOT facility”, A. Heikkinen and T. Linden

Computing in High Energy and Nuclear Physics (CHEP2006), India, February 2006

• Nuclide production by protons on various targets from 20 MeV to 8 GeV

• Bertini cascade hybrid model: intranuclear cascade + preequilibrium + fission + evaporation

• Performance comparable to other codes (HETC, CEM, LAHET, CASCADE)

Efforts for validation of hadronic models ongoing within GEANT4

collaboration, including also the problem of isotope production



Upgrades in codes (II)

The isotope production capabilities in GEANT4 are being validated and improved by the GEANT4 collaboration


“Validation of GEANT4 Bertini Cascade nuclide production using parallel ROOT facility”, A. Heikkinen and T. Linden

Computing in High Energy and Nuclear Physics (CHEP2006), India, February 2006

• Nuclide production by protons on various targets from 20 MeV to 8 GeV

• Bertini cascade hybrid model: intranuclear cascade + preequilibrium + fission + evaporation

• Performance comparable to other codes (HETC, CEM, LAHET, CASCADE)

New models with good isotope production properties are being

incorporated in GEANT4 and planned to be released late in 2007

Our report summarizing activation studies in Te, Ge and Cu has been

forwarded to GEANT4 people to help in this isotope production validation

Efforts for validation of hadronic models ongoing within GEANT4

collaboration, including also the problem of isotope production

• Proposals for Ge experiments

• Plans for other targets: Cu, NaI

An irradiation experiment in Te has been already carried out at CERN with proton beams

S. Cebrián, Cosmogenic Induced Activity IDEA meeting, Zaragoza, November 2005

Irradiation tests

GOAL: to measure the production cross-sections and/or rates of production with n/p beams on the targets of interest in dedicated experiments

Essential to validate and refine calculations with codes

In the first two years …

1 2 3 4

Facility ITEP, Moscow, Russia Svedberg Laboratory (TSL), Uppsala, Sweden

Centre de Reserches du Cyclotron (CRC), Louvain, Belgium

Natural irradiation

Beam 800 MeV p on W target producing n with a continuous energy spectrum Total fluence: 1015 p W target: D=5cm, L=3 cm

Fully monoenergetic n beam 20-175 MeV Fluence: 5 105 n/cm2/s (2-30 cm , up to 106 n/s)

Quasi-monoenergetic n beam 20-65 MeV Fluence: 1.3 104 n/cm2/s (10 cm , up to 2 106 total n/s)

Cosmic rays at sea level

Availability Beam for therapy, industry and basic research. TARI access in 2004-2007

Beam for industry and research.

Gamma counting

Included. Possibility of sending the sample for further measurements.

Not available. Possible.

Cost Irradiation: 3000 € Personnel: 3000 €+ 500 €/sample Gamma counting: 150 €/day Samples: 1.4$/mg 70Ge (buying); 300-500 €/half a year (renting)

Irradiation: 400 €/hour + sample

Irradiation: 516 €/hour for industry. Offered free irradiation if proposal accepted + sample

Sample

More info “Pilot activation experiment at ITEP”, V. Kornoukhov

- http://www.tsl.uu.se - On the beam and facility: L. Andersson et al, Proceedings of EPAC2004, Lucerne, Switzerland.

- http://www.cyc.ucl.ac.be - On the beam and facility: H. Schuhmacher et al, NIMA 421 (1999) 284 - Irradiation experiment in Ge at CRC: J. E. Naya et al, NIMA 396 (1997) 374.


Proposals for Ge irradiation with neutrons

68Ge production seems to be mostly due to low energy neutrons and important discrepancies were found between different estimates

irradiation test to check.


Plans for Ge irradiation with protons

• By Milano group together with American collaborators

• Ge samples

• Proton beams with energies 1.4 and 24 GeV

• At CERN

• Irradiation scheduled to take place within next weeks

Beam irradiation experiment scheduled

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 Cu

• By Modane group in JRA1

• Cu sample of 2250 g

• Exposure to cosmic rays at ~2000 m in Modane

• More than three months of exposure up to now

• Gamma counting foreseen to determine production rates

Natural irradiation experiment underway


Plans for NaI

• 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 in Zaragoza during more than 7 years

Natural irradiation experiment underway

• A rough estimate of the production of some relevant long-lived products has been made, giving some measurable yields (125I, 126I)

• A background measurement with this crystal can be made in the Canfranc Underground Laboratory to check these predictions

Outlook


WP Task

9.R2 - Table 1 – IDEA - Third 18 months Execution Plan

25th to 30th month(1.04.2006-30.09.2006)

31st to 36th month(1.10.2006-31.03.2007)

37th to 42th month(1.04.2007-30.09.2007)

3 B1

Tasks

- Upgrade of n/p activation codes: extension to copper

- Start of a detailed analysis of the activation experiments and of the consequences on Ge and Te based DBD experiments

- Activation tests on Ge- Continuation of activation tests on Te

Milestones and

Deliverables

- Technical report describing the activation experiments

- Progress report


Summary

A detailed report summarizing the activation studies carried

out for Te, Ge and Cu has been delivered, presenting the main

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


An irradiation experiment on Ge with protons is scheduled

and the neutron proposal must be fixed to be performed in the

next future

Other irradiation tests in Cu and in NaI are underway in

collaboration with people from JRA1 in ILIAS, based on long

natural exposures of massive samples to cosmic rays


YIELDS (for 68Ge, 1 g sample)

1, ITEP 2, Uppsala 3, Louvain 4, Nat irradiation

Activity mBq

5787 (for 1 g 70Ge) (V. Kornoukhov)

~25 (for nat Ge after 1 hour of irradiation, assuming =60 mb)

~0.5 (for nat Ge after 1 hour of irradiation, assuming =60 mb and completely monoenergetic beam)

0.3 10-3 (for nat Ge after 1 y of irradiation assuming R=50 kg-1 d-1)

counting at 1077 keV counts/day (I=3%, =2%)

300 1.3 0.026 1.5 10-5

X-rays at 9.2 keV counts/day (I=39.7%, =100%)

~2x105 ~850 ~17 ~0.01

PROS & CONS 1, ITEP 2, Uppsala 3, Louvain 4, Nat irradiation Possibility of seeing other activation products

++ - -- + Continuation with enriched samples

++ - - - Extrapolation of results - + + -

Sample=detector approach:

+ higher efficiency for measuring the yield, allowing lower neutron fluxes

- irradiation of components other than Ge crystal

- not easy continuity for enriched samples

Activity ratios: 10000 : 50 : 1 : 0.001

Only X-ray counting possible

Very massive samples required


1,E-05

1,E-04

1,E-03

1,E-02

1,E-01

1,E+00

1,E+01

1,E+02

10 100 1000 10000 100000

energy (MeV)

sig

ma

(m

b)

Silberberg &Tsao (YIELDX) measurement Berkeley measurement CERN

GEANT4 modified COSMO

60Co production in nat Te


Documents

Cosmogenic induced activity Susana Cebrián [email protected]@unizar.es University of Zaragoza (Spain) IDEA (Integrated Double-beta decay European