Transcript Monte Carlo codes: MUSIC, MUSUN, SOURCES Vitaly Kudryavtsev Department of Physics and Astronomy

Monte Carlo codes: MUSIC, MUSUN,
SOURCES
Vitaly Kudryavtsev
Department of Physics and Astronomy
University of Sheffield
[email protected]
N3-BSNS/JRA1-WP2 - Valencia, 15 April 2005
Vitaly Kudryavtsev
1
MUSIC
• MUon SImulation Code - a code to transport muons through large
thickness of matter (P. Antonioli et al., Astroparticle Physics, 7, 357 (1997);
V. A. Kudryavtsev et al., Phys. Lett. B, 471, 251 (1999):
– Fortran-77, a set of subroutines; two subroutines should be called from the
user’s ‘main’ programme:
o initialization: initialiaze_music
o propagation: muon_transport (a loop should be arranged in the main programme
to transport many muons - only one initialization is required)
–
–
–
–
Inputs: muon coordinates, direction, energy, distance to transport muons;
Outputs: final muon coordinates, direction, energy;
A specific version for each type of the rock should be generated by me;
All processes are treated stochastically if an energy transfer to secondary
particles exceeds 10-3E.
– Uses most recent and accurate cross-sections of muon interactions with matter.
– 3D code: takes into account muon deflection due to multiple Coulomb
scattering and stochastic processes;
N3-BSNS/JRA1-WP2 - Valencia, 15 April 2005
Vitaly Kudryavtsev
2
MUSIC
– Simple and fast (a few seconds to transport 1000 muons to 1 km w. e.);
– Accurate - agrees with GEANT4 and FLUKA (only a few tests have been done,
however); if a difference is found, I would trust MUSIC.
– Tested against experimental data (V. A. Kudryavtsev et al., Phys. Lett. B, 494,
175 (2000); V. A. Kudryavtsev et al. Nuclear Instrum. and Meth. in Phys. Res.
A, 505, 688 (2003); also references therein).
– Used by many groups across the world (LVD, MACRO, SNO, KamLAND,
ANTARES etc.)
N3-BSNS/JRA1-WP2 - Valencia, 15 April 2005
Vitaly Kudryavtsev
3
MUSIC vs experimental data
MUSIC vs LVD data, from M. Aglietta
et al. (LVD Collaboration), Phys. Rev.
D, 58, 092005 (1998).
N3-BSNS/JRA1-WP2 - Valencia, 15 April 2005
MUSIC vs LVD data, from M. Aglietta
et al. (LVD Collaboration), Phys. Rev.
D, 60, 112001 (1999).
Vitaly Kudryavtsev
4
MUSIC vs experimental data
C. Waltham (SNO Collaboration). Proc. ICRC 2001, p. 991.
N3-BSNS/JRA1-WP2 - Valencia, 15 April 2005
Vitaly Kudryavtsev
5
MUSIC vs experimental data
Filled circles - AMANDA
Open circles - Baikal
From V. A. Kudryavtsev
et al., Phys. Lett. B, 494,
175 (2000).
N3-BSNS/JRA1-WP2 - Valencia, 15 April 2005
Vitaly Kudryavtsev
6
MUSIC vs experimental data
A. Tang (Chinese
University of
Hong Kong),
personal
communication
N3-BSNS/JRA1-WP2 - Valencia, 15 April 2005
Vitaly Kudryavtsev
7
MUSUN
• You may not need to propagate muons each time you want to simulate
neutrons. Muon propagation can be done once and muon energy spectra
and angular distributions stored to be used in future.
• MUon Simulations UNderground - a code to generate muons underground
(V. A. Kudryavtsev et al., Phys. Lett. B, 494, 175 (2000); V. A. Kudryavtsev
et al. Nuclear Instrum. and Meth. in Phys. Res. A, 505, 688 (2003)). The
code uses the results from MUSIC:
– Fortran-77, a set of subroutines; two subroutines should be called from the
user’s ‘main’ programme:
o initialization: initialiaze
o sampling muons: sampling (a loop should be arranged in the main programme to
sample many muons - only one initialization is required)
– Inputs: vertical depth (simple version of MUSUN assumes flat surface above
the lab; more complex mountain profile is also possible on request - LNGS
version exists), range of energies, angles;
– Outputs: muon direction, energy (also sampling on a surface of a
parallelepiped is possible - muon coordinates);
N3-BSNS/JRA1-WP2 - Valencia, 15 April 2005
Vitaly Kudryavtsev
8
SOURCES
• Neutron production via spontaneous fission and (,n) reactions:
SOURCES-4A (Wilson et al. SOURCES4A, Technical Report LA-13639MS, Los Alamos, 1999) - neutron flux and energy spectrum from U/Th;
the latest version SOURCES-4C.
• Features:
– Input - radioactive isotope concentrations, material;
– Output - neutron energy spectra from each radioactive isotope in each
material;
– In addition to thick target neutron yields also interface problems, alphaparticle beams etc.
– Watt spectrum for spontaneous fission;
– Measured or calculated (GNASH) (,n) cross-sections (library - can be
modified);
– Transition probabilities to the excited states (nuclide level branching ratios) mainly GNASH calculations (library - can be modified);
– Stopping power for alphas.
N3-BSNS/JRA1-WP2 - Valencia, 15 April 2005
Vitaly Kudryavtsev
9
SOURCES-4A
• Problems:
– Alphas below 6.5 MeV only;
– Some cross-sections are missing (energy threshold for these reactions is
higher than 6.5 MeV);
– Cross-sections needed updating;
– Transition probabilities to the excited states are present up to 6.5 MeV only.
• Modifications to SOURCES:
– 6.5 MeV upper limit removed (now 10 MeV limit for alphas);
– Some cross-sections already present in the code library extended to higher
energies using available experimental data;
– Some cross-section updated according to recent experimental results (Na);
– New cross-sections added (35Cl, 54Fe, Cu);
– Probability of transitions to the excited states at high energies of alphas are
as at 6.5 MeV (this overestimates the neutron energy);
– For new cross-sections - all transitions to the ground state only.
N3-BSNS/JRA1-WP2 - Valencia, 15 April 2005
Vitaly Kudryavtsev
10
SOURCES-4A
•
•
Cross-sections on heavy (Fe) targets - too few measurements: for example Fe - only
54Fe cross-section has been measured.
Calculated cross-sections should be used; where to find them?
– GNASH-FKK code (www.nea.fr/abs/html/psr-0125.html)?
– Recipe can also be found in: Estimation of Unknown Excitation Functions and Thick
Target Yields for p, d, 3He and alpha Reactions. Series: Landolt-Börnstein: Numerical
Data and Functional Relationships in Science and Technology - New Series; Group 1:
Elementary Particles, Nuclei and Atoms Vol. 5: Q-Values and Excitation Functions of
Nuclear Reactions. Part c; Keller, K.A., Lange, J., Münzel, H. 1974, VI, 257 pp. 506 figs.,
Hardcover, ISBN: 3-540-06723-X (Springer).
– Rachid Lemrani (Saclay) found a code EMPIRE, which calculates the cross-sections.
•
•
•
•
Note that Coulomb barrier suppress significantly the cross-sections for high-Z
elements even if the energy threshold (calculated from the Q-value of the reaction
is small); for Fe-Cu the Coulomb barrier is about 7.0-7.2 MeV.
Transition probabilities are absent for E > 6.5 MeV and for all heavy targets.
Accuracy: 50-70% for Fe and stainless steel if compared to the Heaton’s estimates.
Updated library of the cross-sections and transition probabilities will be kept in
the code repository. Please, put your updates there marking clearly the date and
name and summary of the update!!!
N3-BSNS/JRA1-WP2 - Valencia, 15 April 2005
Vitaly Kudryavtsev
11
Neutron production spectra
•
•
•
N3-BSNS/JRA1-WP2 - Valencia, 15 April 2005
Neutron production spectrum in NaCl
(from modified SOURCES-4A): 60 ppb
U, 300 ppb Th - mainly (,n).
Neutron production rate in NaCl 1.0510-7 cm-3 s-1 agrees with other
calculations.
Major problem: neutron energy
spectrum in the laboratory (after
propagation) is softer than measured at
Modane (Chazal et al. Astropart. Phys.
9 (1998) 163; revised recently - Gerbier
et al. TAUP2003), Gran Sasso (Arneodo
et al. Nuovo Cimento A112 (1999) 819)
and CPL (Korea) (Kim et al. Astropart.
Phys. 20 (2004) 549) and also softer
than other simulations.
Vitaly Kudryavtsev
12
Neutron production spectra
5.0 MeV alphas - Al2O3
5.5 MeV alphas - Mg (natural)
Energy spectrum of neutrons from 5.0 MeV alphas incident on aluminum
oxide slab (left) and from 5.5 MeV alphas incident on magnesium slab
(right) as calculated by SOURCES 4A (from SOURCES manual) and
compared to measured data (Jacobs and Liskien, Annals of Nuclear
Energy, 10 (1983) 541).
N3-BSNS/JRA1-WP2 - Valencia, 15 April 2005
Vitaly Kudryavtsev
13