IAEA Benchmark of Spallation Models

IAEA Benchmark of Spallation Models - Specifications

Participation

Participants should comply with all the rules listed below otherwise their contribution will not be considered.

The code used by the participants should be able to treat the complete reaction mechanism, i.e. contain a description of the first stage of the reaction by an intranuclear cascade, a QMD or a BUU model followed by a de-excitation stage, with optionally an intermediate pre-equilibrium stage. Code developers working on a model describing only one stage of the interaction could contact the organizers to have, if this is possible, their code coupled to a code describing the other stage of the reaction mechanism.
Participants should provide a short but complete write-up of their model(s) with references to most relevant published papers and give a comprehensive description of all the physics ingredients and parameters used for the present benchmark
Participants should provide the organizers with the source code in the version used for the benchmark. The organizers commit themselves not distributing it to anyone else.
Participants should calculate the whole mandatory set of experimental data which has been chosen as limited as possible but covering the full range of energy, mass and reaction channels.
An additional set of experimental data will be provided for participants wanting a more thorough comparison of their model. Participants are encouraged to calculate it.
Additionally, some information regarding mostly the characteristics of the remnant nucleus at the end of the first stage of the reaction (INC, INC+PE, QMD or BUU) that will serve as inputs for the de-excitation stage will be requested. This is necessary for understanding the physical behavior of the different models.
Calculations with one model should be done with the same set (default preferentially) of parameters. One participant can provide calculations with several versions of the models but for each should calculate the whole set of mandatory data and provide the detailed description of the parameters for each version.
Participants should provide the organizers with the results of the calculations in the requested format. Results should be given with the statistical error of the calculation.

Domain

N + A, 20 MeV to 3 GeV, A≥12

The benchmark is restricted to nucleon-induced reactions on nuclei from carbon to uranium. Although, in principle, intranuclear cascade models are based on physics assumptions not valid below a hundred of MeV, it has been decided to have comparisons to data mostly above 100 MeV but with a few sets at low incident energies. The reason is that, in many cases, simulation code users perform calculations in which the models are used down to 20 MeV, at least for certain isotopes. This happens in particular because

20-150 MeV libraries are not available for all isotopes
when using libraries below 150 MeV residue production can be calculated only through activation libraries not available or not totally reliable in the whole energy range for all isotopes
the use of libraries does not allow taking into account correlations between particles

The goal of the benchmark is to test the physics models either presently used or which could be used in the future in high-energy transport codes to compute the production yields and properties of particles and nuclei emitted in a fundamental spallation interaction. Therefore, only comparisons with elementary experimental data on thin targets will be considered.

The list of available Experimental Data Sets for which calculations should be performed is available here.

Model ingredients and parameters

List of model ingredients and parameters to be provided by the participant:

Parameters of first stage model (INC, INC+PE, QMD, BUU...)
- N-N interaction elastic and inelastic cross-sections
- Nuclear medium description (continuous medium, individual nucleons, pseudo-particles...)
- In medium corrections of N-N interaction or not
- Nuclear average potential : V_N,V_π
- Nuclear shape description
- Production of composite particles during the cascade stage or not. If yes, parameters of the coalescence mechanism description
- Implementation of the Pauli blocking and related parameters
- Pre-equilibrium or no. If yes, parameters of the pre-equilibrium model, criterion to switch from INC to pre-equilibrium and from pre-equilibrium to de-excitation
- If no-pre-equilibrium, criterion to switch from INC to de-excitation
- Range of validity in energy and mass
- Computational time (time per event for a typical case and indication of the platform)
- ...
Parameters of de-excitation models
- level densities
- Inverse reaction cross-sections: ?inv including Coulomb barriers for the different types of evaporated particles
- Fission barriers
- Fission fragment generation
- List of de-excitation channels and related parameters
- Capability of the model to handle isomers
- ...

Formatting the Results

Particle cross sections

Double-differential cross-sections of neutrons, protons, pions, deuterons, tritons, ³He, alphas, etc. at different angles should be provided as one single file containing d²σ/dΩ/dE for each angle + angle-integrated, energy integrated and total production cross-sections, according to the following scheme:

Energy		Angle 1		Angle 2		...		Angle integrated
Energy [MeV]	Energy bin [MeV]	d²σ/dΩ/dE [mb/sr/MeV]	error [mb/sr/MeV]	d²σ/dΩ/dE [mb/sr/MeV]	error [mb/sr/MeV]	.	.	dσ/dE [mb/MeV]	error [mb/MeV]
E1	ΔE1	.	.	.	.	.	.	.	.
E2	ΔE2	.	.	.	.	.	.	.	.
...	...	.	.	.	.	.	.	.	.
Energy integrated dσ/dΩ[mb/sr] error[mb/sr]		.	.	.	.	.	.	Energy and Angle integrated σ[mb] error[mb]

For each calculation, results should be given as ASCII text files, named:

beam_target_energy_observable_participant.txt

where observable = ddxsn, ddxsp, ddxspi+, ddxspi-, ddxsd, ddxst, ddxs3he, ddxsa... for double-differential production cross-sections of respectively neutrons, protons, pions, deuterons, tritons, 3He, alpha...

Example: p_Fe56_800_ddxsn_cem03.txt for neutron production double-differential cross-section calculated for p+⁵⁶Fe at 800 MeV with CEM03.

Multiplicities

Average multiplicities will be generated by the organisers from the energy and angle integrated cross-sections.

Neutron multiplicity distributions should be generated by the participants using the detector efficiency function:

Efficiency (Ekin) =  0.820652 + 0.00689154 * Ekin - 0.00423934 * Ekin**2 + 0.000370167 *Ekin**3
                       - 1.80244E-05 * Ekin**4 + 5.20070E-07 * Ekin**5 - 8.97261E-09 * Ekin**6 
                       + 9.06944E-11 *Ekin**7 - 4.95096E-13 * Ekin**8 + 1.12679E-15 *Ekin**9  
                                                                        ;for  Ekin  < 90 MeV 

Efficiency (Ekin) =  0.122239   ;for  Ekin  > 90 MeV

Isotope production cross sections (isotopic distributions)

Isotopic distribution data file should contain: Z, A, σ (mb), error (mb). For each calculation, results should be given as ASCII text files, named:

beam_target_energy_iso_participant.txt

Example: p_Fe56_1000_iso_cem03.txt for isotopic distributions calculated with CEM03 to be compared to experimental data obtained at GSI in the reaction ⁵⁶Fe (1000 MeV/u) + p.

Isotope production cross sections (excitation functions of activation cross-sections

Excitation functions will be generated from primary isotopic cross-sections at the different energies calculated by the participant. Participants are free to choose the number of energies they want to calculate between 20 MeV and 3 GeV.

The cumulative cross-sections, i.e. cross sections including the cross sections of parent nuclei after their total decay in addition to the referred nucleus, will be generated by the organizers in order to be compared to experimental data.

For data sets on natural targets, participants can either calcute directly with the proper isotope composition or provide separate files for all the isotopes entering in the natural composition. In the latter case, the organisers will generate the results for natural target.

For each energy, results should be given as one ASCII text file, containing : Z, A, σ(Ei), error(Ei), named:

beam_target_energy_excfun_participant.txt

Example: p_Pbnat_500_excfun_cem03.txt for calculations done directly with the natural isotope composition, or p_Pb206_500_excfun_cem03.txt; p_Pb207_500_excfun_cem03.txt; ...

Isotope production cross sections (isomers)

For participants able to predict isomer production, the results concerning isomer production crossections should be added in the file as a line beginning with a number equal to Z+100 (Z+200 for a second state). For instance, if 2 isomers of ¹²⁴Sb are produced:

....
50 122 56.8 5.6
51 124 25.2 2.5
151 124 10.5 1.0
251 124 2.3 0.2
52 125 ......
....

Units

Energies and energy bins should be in MeV, cross-sections and errors in mb except for pions in which case they should be given in μb.

Optional

Participants are encouraged to provide in addition results as PAW ntuples or ROOT trees containing for each event the characteristics (Z, A, E, theta, phi) of all particles and nuclei.

Additional information

For each different calculated system (for which several files may have been provided) a file containing additional information about reaction cross-sections, remnant characteristics and multiplicities should be provided and named:

beam_target_energy_info_participant.txt

Example: p_Fe_800_info_cem03.txt.

The file should contain:

Reaction cross-section
1. given by the model, σ_R (σ_geom x N_inel / N_evts)
2. used for normalisation, σ'_R (if different from σ_R)
Characteristics of the remnant nucleus at the end of the first stage of the reaction (INC, INC+PE, QMD or BUU) that will serve as inputs for the de-excitation stage, mean values and distributions:
1. Excitation energy, E^*
2. charge, Z_R
3. mass, A_R
4. excitation energy per nucleon, E^*/A_R
5. bi-dimensional plot of E^* versus A_R (if possible)
6. recoil velocity, p_R
7. angular momentum, J_R
Multiplicities of all types of particles emitted in each stage of the reaction (INC, QMD or INC+Pre-eq and de-excitation)
1. Neutron multiplicities, Mn[INC], Mn[deex]
2. Proton multiplicities, Mp[INC], Mp[deex]
3. Light charged particles (deuterons to alphas), Md[INC], Md[deex], Mt[INC], Mt[deex]
4. Pion multiplicities, M?+[INC], M?-[INC], M?0[INC]

Participants able to generate PAW ntuples (or ROOT trees) can provide a file named:

beam_target_energy_participant.hbk

Experimental Data Sets

Participants should calculate the whole set of quantities for which experimental data are given in the mandatory data set. The list has been chosen as limited as possible but covering the full range of energy, mass and reaction channels considered appropriate for the present benchmark.