Transcript Document

Cosmogenic induced activity
IDEA (Integrated Double-beta decay European Activities)
Task coordinators: Maura Pavan, Susana Cebrián
Susana Cebrián
[email protected]
University of Zaragoza (Spain)
Prague, 20th-21st April 2006
 Implementation plan
9.R2 - Table 1 – IDEA - Second 18 months Execution Plan
WP
Task
13st to 18th month
(1.04.2005-30.09.2005)
- Up-grade and
development of
simulation codes
Tasks
4
B1
19th to 24th month
(1.10.2005-31.03.2006)
- Upgrading of existing
codes for n/p activation
- Design of further n/p
activation tests on Ge
and TeO2
25th to 30th month
(1.04.2006-30.09.2006)
- further n/p activation
experiments
- Start-up of tests at CERN and other labs on Ge
and TeO2
Milesto
nes and
Delivera
bles
- Upgraded codes for n/p activation and related
technical report
- progress report
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
 General issues
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. Villar
AIP (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.
Villar
To appear in Journal of Physics: Conference Series, IoP, (Proceedings of the TAUP2005
Conference, Zaragoza, Spain, September 2005).
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
IDEA meeting, Prague, April 2006
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: 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
S. Cebrián, Cosmogenic Induced Activity
IDEA meeting, Prague, April 2006
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
S. Cebrián, Cosmogenic Induced Activity
IDEA meeting, Prague, April 2006
Cosmic neutron spectrum: parameterization based on measurements
R   dE  ( E ) n ( E )
A  R (1  e
 texp
)e tdec
E>20 MeV:
4.5 10-3 n/cm2/s
J. F. Ziegler, IBM Journal of Research and Development 42 (1998) 1.
S. Cebrián, Cosmogenic Induced Activity
IDEA meeting, Prague, April 2006
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
S. Cebrián, Cosmogenic Induced Activity
IDEA meeting, Prague, April 2006
General conclusions on codes (I)
From simulation of irradiation experiments…
 At high energies, in GEANT4 the Bertini model gives the best agreement
with measurements
Deviation
factors
Bertini
cascade
Binary
cascade
Te, ~1.8 GeV
Ge, 660 MeV
~2
3.2
>10
5.9
YIELDX
~3
1.9
 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
IDEA meeting, Prague, April 2006
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
S. Cebrián, Cosmogenic Induced Activity
YIELDX predictions, very good at high energies,
worsen in the medium energy range
IDEA meeting, Prague, April 2006
General conclusions on codes (III)
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
 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
IDEA meeting, Prague, April 2006
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 DA, 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
S. Cebrián, Cosmogenic Induced Activity
IDEA meeting, Prague, April 2006
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
S. Cebrián, Cosmogenic Induced Activity
IDEA meeting, Prague, April 2006
Upgrades in codes (II)
Monte Carlo codes: GEANT4
 Efforts for validation of hadronic models ongoing within GEANT4
collaboration, including also the problem of isotope production
“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)
S. Cebrián, Cosmogenic Induced Activity
IDEA meeting, Prague, April 2006
S. Cebrián, Cosmogenic Induced Activity
IDEA meeting, Prague, April 2006
Upgrades in codes (II)
Monte Carlo codes: GEANT4
 Efforts for validation of hadronic models ongoing within GEANT4
collaboration, including also the problem of isotope production
“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
The isotope production capabilities in GEANT4 are being validated and
improved by the GEANT4 collaboration
S. Cebrián, Cosmogenic Induced Activity
IDEA meeting, Prague, April 2006
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 …
An irradiation experiment in Te has been already
carried out at CERN with proton beams
• Proposals for Ge experiments
• Plans for other targets: Cu, NaI
S. Cebrián, Cosmogenic Induced Activity
IDEA meeting, Zaragoza, November 2005
Proposals for Ge irradiation with neutrons
1
2
ITEP, Moscow, Russia
Svedberg Laboratory (TSL),
Uppsala, Sweden
800 MeV p on W target
Fully monoenergetic n
producing n with a
beam 20-175 MeV
continuous energy spectrum Fluence: 5 105 n/cm2/s (2Total fluence: 1015 p
30 cm , up to 106 n/s)
W target: D=5cm, L=3 cm
Facility
Beam
Availability
Gamma
counting
Cost
More info
Included. Possibility of sending
the sample for further
measurements.
Irradiation: 3000 €
Personnel: 3000 €+ 500
€/sample
Gamma counting: 150 €/day
Samples: 1.4$/mg 70Ge
(buying); 300-500 €/half a year
(renting)
“Pilot activation experiment at
ITEP”, V. Kornoukhov
3
Centre de Reserches du Cyclotron
(CRC), Louvain, Belgium
Quasi-monoenergetic n beam 20-65
MeV
Fluence: 1.3 104 n/cm2/s (10 cm ,
up to 2 106 total n/s)
Beam for therapy, industry and
basic research.
TARI access in 2004-2007
Not available.
Beam for industry and research.
Irradiation: 400 €/hour
+ sample
Irradiation: 516 €/hour for industry.
Offered free irradiation if proposal
accepted
+ sample
- 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.
4
Natural
irradiation
Cosmic
rays at sea
level
Possible.
Sample
68Ge
production seems to be mostly due to low energy neutrons and
important discrepancies were found between different estimates
irradiation test to check.
S. Cebrián, Cosmogenic Induced Activity
IDEA meeting, Prague, April 2006
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
• Irradiation scheduled to take place within next weeks
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.
S. Cebrián, Cosmogenic Induced Activity
IDEA meeting, Prague, April 2006
Plans for Cu
 Natural irradiation experiment underway
• 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
S. Cebrián, Cosmogenic Induced Activity
IDEA meeting, Prague, April 2006
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 in Zaragoza during more than 7 years
• 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
S. Cebrián, Cosmogenic Induced Activity
IDEA meeting, Prague, April 2006
Outlook
9.R2 - Table 1 – IDEA - Third 18 months Execution Plan
WP
Task
25th
30th
to
month
(1.04.2006-30.09.2006)
31st
36th
to
month
(1.10.2006-31.03.2007)
- Upgrade of n/p activation codes: extension to
copper
Tasks
3
- Activation tests on Ge
- Continuation of activation tests on Te
B1
Milestones - Technical report describing the activation
and
experiments
Deliverables
S. Cebrián, Cosmogenic Induced Activity
37th to 42th month
(1.04.200730.09.2007)
- Start of a detailed
analysis of the
activation experiments
and of the
consequences on Ge
and Te based DBD
experiments
- Progress report
IDEA meeting, Prague, April 2006
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
S. Cebrián, Cosmogenic Induced Activity
IDEA meeting, Prague, April 2006
YIELDS
1, ITEP
2, Uppsala
3, Louvain
4, Nat irradiation
5787
~25
~0.5
0.3 10-3
68
(for Ge, 1 g sample)
Activity
mBq
(for 1 g 70Ge)
(V. Kornoukhov)
(for nat Ge after 1 hour of
irradiation, assuming =60 mb)
Activity ratios: 10000 : 50 : 1 : 0.001
 counting at 1077 keV
counts/day
(I=3%, =2%)
X-rays at 9.2 keV
counts/day
(I=39.7%, =100%)
(for nat Ge after 1 hour of (for nat Ge after 1 y of
irradiation, assuming =60 irradiation assuming R=50
kg-1 d-1)
mb and completely
monoenergetic beam)
300
1.3
0.026
1.5 10-5
~2x105
~850
~17
~0.01
Only X-ray
counting
possible
Sample=detector approach:
+ higher efficiency for measuring the yield, allowing lower neutron fluxes
Very
massive
samples
required
- irradiation of components other than Ge crystal
- not easy continuity for enriched samples
PROS & CONS
Possibility of seeing other
activation products
Continuation with
enriched samples
Extrapolation of results
1, ITEP
2, Uppsala
3, Louvain
4, Nat irradiation
++
-
--
+
++
-
-
-
-
+
+
-
S. Cebrián, Cosmogenic Induced Activity
IDEA meeting, Prague, April 2006
1,E+02
1,E+01
sigma (mb)
1,E+00
1,E-01
1,E-02
1,E-03
1,E-04
60Co
1,E-05
10
100
production in nat Te
1000
10000
100000
energy (MeV)
Silberberg &Tsao (YIELDX)
GEANT4
S. Cebrián, Cosmogenic Induced Activity
measurement Berkeley
modified COSMO
measurement CERN
IDEA meeting, Prague, April 2006