Recent development for lowenergy package

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Recent development for lowenergy package

• V.Ivanchenko
• Budker Institute for Nuclear Physics
• Novosibirsk, Russia

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Main activity in 2002

• Electron ionisation
• Electrom Bremssrahlung
• Hadron ionization
• GenericIons ionisation
• Interface to deexcitation module
• Fluctuations

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Electron energy loss in G4 lowenergy package

• Is based on EEDL database data on cross sections
  and spectra
• In G4 3.2 there were serious problems in electron
  processes
• Redesign electron physics is available from 4.0,
  4.1-ref-02 fix main problems
• Parameterization of 7650 atomic shells

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Electron bremsstrahlung in G4 4.0
F(x) parametrised from EEDL. At high energies
Continuous energy loss
Direction of the outgoing electron the same as
that of the incoming one angular distribution of
emitted photons generated according to a
simplified formula based on the Tsai cross
section (expected to become isotropic in the
low-E limit)
Gamma ray production
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Electron ionisation in G4 4.0
Bs is the binding energy of sub-shell s
Continuous energy loss
Value of coefficient A for each element is
obtained from fit to EEDL data for energies
available in the database
d-electron production
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Problems of G4 4.0 parameterization

• 50 of level spectra for ionization had problems
• For part of atoms dE/dx was not fit standard
  results at 1-10 MeV energy region
• Bremsstrahlung spectra at max energies do not fit
  standard

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Solutions for G4 4.1

• For both processes for each shell and atom energy
  scale for secondary is subdivided on 2 parts
  one the same as G4 4.0, in second value A is
  parameterized
• Results of comparison EEDL data and ionization
  parameterization
• 3034 shells are inside 1
• 4448 shells are inside 10
• 168 shells are outside 10
• Average RMS 2.2 (17 in G4 4.0)

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Comparison with SANDIA electron data

• Ionisation profile in media from 1MeV electron
  strongly depends on multiple scattering
• LowEnergy package has small advantage to standard
  for small step sizes

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Delta-electron production
Si
Be
10
Delta-electron production
Fe
Pb
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Bremsstahlung
Si
Be
12
Bremsstahlung
Fe
Pb
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Current problems

• Angular spectrum of Bremsstrahlung for low
  energies
• 168 non perfect shells
• 1 10 MeV energy range for some elements has
  problems
• Range artifact

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Hadron ionisation
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Hadron ionisation

• For the proton energy range 1-2 MeV are not
  perfect for some atoms for all available models
• SRIM-2000 parameterization are welcome

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Ion ionisation

• Ionisation for GenericIons in G4 4.1
• Bragg peak position and right side are perfect
• Left side is not so precise

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Conclusions and plans

• List of problems to be fixed to G4 5.0
• Range artifact
• Fluo artifact
• Range of heavy ions
• Angular distribution for Bremsstrahlung can be
  improved
• SRIM-2000 for hadrons and ions?
• Model approach will improve quality