[ Identification | Description | Input parameters | Output parameters | Links ]
Source_gen
ComponentThis routine is a neutron source (rectangular or circular), which aims at a square target centered at the beam (in order to improve MC-acceptance rate). The angular divergence is then given by the dimensions of the target. The neutron energy/wavelength is distributed between Emin=E0-dE and Emax=E0+dE or Lmin=Lambda0-dLambda and Lmax=Lambda0+dLambda. The I1 may be either arbitrary (I1=0), or specified in neutrons per steradian per square cm per Angstrom. A Maxwellian spectra may be selected if you give the source temperatures (up to 3). The source shape is defined by its radius, or can alternatively be squared if you specify non-zero h and w parameters. The beam is spatially uniform, but becomes gaussian if one of the source dimensions (radius, h or w) is negative, or you set the gaussian flag. Divergence profiles are triangular. The source may have a thickness, which will broaden the default zero time distribution. For the Maxwellian spectra, the generated intensity is dPhi/dLambda (n/s/AA) For flat spectra, the generated intensity is Phi (n/s). Usage example: Source_gen(radius=0.1,Lambda0=2.36,dLambda=0.16, T1=20, T2=38, I1=1e13) Source_gen(h=0.1,w=0.1,Emin=1,Emax=3, I1=1e13, verbose=1, gaussian=1) EXTEND %{ t = rand0max(1e-3); // set time from 0 to 1 ms for TOF instruments. %} Some sources parameters: PSI cold source T1=150.42,I1=3.67e11 T2=38.74,I2=3.64e11 T3=14.84,I3=0.95e11 ILL VCS cold source T1=216.8,I1=1.24e+13,T2=33.9,I2=1.02e+13 (H1) T3=16.7 ,I3=3.0423e+12 ILL HCS cold source T1=413.5,I1=10.22e12,T2=145.8,I2=3.44e13 (H5) T3=40.1 ,I3=2.78e13 ILL Thermal tube T1=683.7,I1=0.5874e+13,T2=257.7,I2=2.5099e+13 (H12) T3=16.7 ,I3=1.0343e+12 ILL Hot source T1=1695,I1=1.74e13,T2=708,I2=3.9e12 %VALIDATION Feb 2005: output cross-checked for 3 Maxwellians against VITESS source I(lambda), I(hor_div), I(vert_div) identical in shape and absolute values Validated by: K. Lieutenant
Name | Unit | Description | Default |
---|---|---|---|
radius | m | Radius of circle in (x,y,0) plane where neutrons are generated. You may also use 'h' and 'w' for a square source | 0.0 |
dist | m | Distance to target along z axis. | 57.296 |
xw | m | Width(x) of target. If dist=0.0, xw = horz. div in deg | 0 |
yh | m | Height(y) of target. If dist=0.0, yh = vert. div in deg | 0 |
E0 | meV | Mean energy of neutrons. You may also use Lambda0. | 14.68 |
dE | meV | Energy spread of neutrons, half width. | 0 |
Lambda0 | AA | Mean wavelength of neutrons. | 2.36 |
dLambda | AA | Wavelength spread of neutrons,half width | 0.1627 |
I1 | 1/(cm**2*st*AA) | Source flux per solid angle, area and Angstrom | 0 |
h | m | Source y-height, then does not use radius parameter | 0 |
w | m | Source x-width, then does not use radius parameter | 0 |
gaussian | 0/1 | Use gaussian beam, normal distributions | 0 |
verbose | 0/1 | display info about the source. -1 unactivate source. | 0 |
T1 | K | Temperature of the Maxwellian source, 0=none | 0 |
Lmin | AA | Minimum wavelength of neutrons | 0 |
Lmax | AA | Maximum wavelength of neutrons | 0 |
Emin | meV | Minimum energy of neutrons | 0 |
Emax | meV | Maximum energy of neutrons | 0 |
T2 | K | Second Maxwellian source Temperature, 0=none | 0 |
I2 | 1/(cm**2*st*AA) | Second Maxwellian Source flux | 0 |
T3 | K | Third Maxwellian source Temperature, 0=none | 0 |
I3 | 1/(cm**2*st*AA) | Third Maxwellian Source flux | 0 |
length | m | Source z-length, not anymore flat | 0 |
Name | Unit | Description | Default |
---|---|---|---|
p_in | |||
lambda0 | |||
lambda02 | |||
L2P | |||
lambda_0 | |||
d_lambda | |||
lambda0b | |||
lambda02b | |||
L2Pb | |||
lambda0c | |||
lambda02c | |||
L2Pc |
Source_gen.comp
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[ Identification | Description | Input parameters | Output parameters | Links ]
Generated automatically by McDoc, Peter Willendrup <peter.willendrup@risoe.dk> / Wed Oct 8 18:18:17 2008