Please someone tell me why is there a difference in the path length of alpha particle in Boron-10 using TRIM and SRIM than the Geant4 Simulation?
The path length of alpha particle with energy 1.47 MeV in Boron-10 is found to be 3.6 micron meters using TRIM and SRIM software.
But when I am simulating in Geant4 the path length is found to be 2.82 micron meter.
In Geant4.10.01 I am using Basic B2 example with QGSP_BERT_HP physics list. I am changing Target material to Boron-10 and particle to neutron.
The target material length is 1 micron meter and radius of target material is also 1 micrometer.I am finding that alpha 1.47 MeV is deposited in 2.82 micron meter of Boron-10 itself.
Why there is a difference in the path length?
My experience with SRIM/TRIM is to model alpha particle transport. According to your question, it seems that you employed SRIM for alpha-particle transport in Boron-10. In GEANT, you simulated neutron transport. This might be the reason for the differences.
Apart from that, SRIM employes different techniques than GEANT, although some codes are common in alpha particle transport. SRIM is lighter in CPU time and does not necessitate use of C++.
Boron-10 is well known as a neutron detector.
With kind Regards
D.Nikolopoulos
Make sure that you're using same density for Boron-10 in TRIM and Geant4
In the docs for SRIM/TRIM and GEANT, you can find which mathematical model was used to calculate range and energy deposition. They are not the same. Not everyone that uses these models agrees on which one is best, in part because experimental results are not always consistent, probably because even sample condition/crystal structure can have an influence. Your two ranges are only 30% apart, which is pretty good.
Checking the density is also a good tip, thanks Samer.
Finally, from your description (Basic B2 example?) I cannot figure out exactly what you simulated. It seems you are trying to determine the range of an alpha in a 1 by 1 um B-10 cylinder. Is this the best choice of geometry, given that the range is most likely >1 um?
Best regards,
Thorwald.
Thanks Thorwald. Also I would try QGSP_BIC_HP physics list and compare.
Dimitrios is right when stating that TRIM and GEANT use different methods: SRIM/TRIM applies the semi-empirical model of Ziegler, Biersack and Littmark, whereas GEANT is a Monte-Carlo toolkit using interaction cross-sections that are either directly measured or extrapolated. It is quite usual that the results of the two codes do not fully agree. Typical errors are 10% or even larger.
For your application, the stopping of low energy ions, SRIM/TRIM is usually more accurate than GEANT and less fault-prone. You find details about the SRIM implementation and comparisons to data in the SRIM Textbook by James Ziegler (see first link).
A third method to check your result is the NIST ASTAR webtool that simulates stopping of Alphas in various materials. Just follow the second link.
PS: It don't think you simulated neutrons in GEANT because then the mean range should be much larger than for Alpha-particles.
http://www.srim.org/SRIM%20Book.htm
http://physics.nist.gov/PhysRefData/Star/Text/ASTAR.html
In your Geant4 calculation you employed a model dedicated to hadronic transport, but not specifically dedicated to the transport of alpha particles.
SRIM (previously TRIM) is dedicated to the transport of ions through absorbers. In the code, the physic mechanism of the ion-ion scattering is treated employing the universal screening potential (determined by Ziegler and collaborators using a large set of experimental data), which describes the interatomic potential.
The universal screeing potential is also used by ICRU-93 (ICRUM - International Commission on Radiation Units and Measurements - (1993), Stopping Powers and Ranges for Protons and Alpha Particles, ICRU Report 49, Bethesda, MD.) whose data set is implemented in the ASTAR code from NIST (http://www.nist.gov/pml/data/star/).
Thus, a sizable difference in the two results can occur, in particular at low energies.
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