[ 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). A high-energy tail of shape A/(lambda0-lambda) is added by setting the HEtailA and HEtailL0 parameters. Finally, a file with the flux as a function of the wavelength [lambda(AA) flux(n/s/cm^2/st/AA)] may be used with the 'flux_file' parameter. Format is 2 columns free text. Additionl distributions for the horizontal and vertical phase spaces distributions (position-divergence) may be specified with the 'xdiv_file' and 'ydiv_file' parameters. Format is free text, requiring a comment line '# xylimits: pos_min pos_max div_min div_max' to set the axis of the distribution matrix. All these files may be generated using standard monitors (better in McStas/PGPLOT format), e.g.: Monitor_nD(options="auto lambda per cm2") Monitor_nD(options="x hdiv, all auto") Monitor_nD(options="y vdiv, all auto") 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 divergence uniform,. 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,I1=1e13,xw=0.01,yh=0.01) Source_gen(h=0.1,w=0.1,Emin=1,Emax=3,I1=1e13,verbose=1,xw=0.01,yh=0.01) EXTEND %{ t = rand0max(1e-3); // set time from 0 to 1 ms for TOF instruments. %} Some sources parameters: PSI cold source T1= 296.16, I1=8.5E11, T2=40.68, I2=5.2E11 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 |
---|---|---|---|
flux_file | str | Name of a two columns [lambda flux] text file that contains the wavelength distribution of the flux in [1/(s*cm**2*st*AA)]. Comments (#) and further columns are ignored. Format is compatible with McStas/PGPLOT wavelength monitor files. When specified, temperature and intensity values are ignored. | 0 |
xdiv_file | str | Name of the x-horiz. divergence distribution file, given as a free format text matrix, preceeded with a line '# xylimits: xmin xmax xdiv_min xdiv_max' | 0 |
ydiv_file | str | Name of the y-vert. divergence distribution file, given as a free format text matrix, preceeded with a line '# xylimits: ymin ymax ydiv_min ydiv_max' | 0 |
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. | 0 |
xw | m | Width(x) of target. If dist=0.0, xw = full horz. div in deg | 0 |
yh | m | Height(y) of target. If dist=0.0, yh = full vert. div in deg | 0 |
E0 | meV | Mean energy of neutrons. | 0 |
dE | meV | Energy spread of neutrons, half width. | 0 |
Lambda0 | AA | Mean wavelength of neutrons. | 0 |
dLambda | AA | Wavelength spread of neutrons,half width | 0 |
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 |
verbose | 0/1 | display info about the source. -1 unactivate source. | 0 |
T1 | K | Temperature of the Maxwellian source, 0=none | 0 |
flux_file_perAA | 1 | When true (1), indicates that flux file data is already per Angstroem. If false, file data is per wavelength bin. | 0 |
flux_file_log | 1 | When true, will transform the flux table in log scale to improve the sampling. This may also cause | 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 |
HEtailA | 1/(cm**2*st*AA**2) | Amplitude of heigh energy tail | 0 |
HEtailL0 | AA | Offset of heigh energy tail | 0 |
Name | Unit | Description | Default |
---|---|---|---|
p_in | |||
lambda0 | |||
lambda02 | |||
L2P | |||
lambda0b | |||
lambda02b | |||
L2Pb | |||
lambda0c | |||
lambda02c | |||
L2Pc | |||
pTable | |||
pTable_x | |||
pTable_y | |||
pTable_xmin | |||
pTable_xmax | |||
pTable_xsum | |||
pTable_ymin | |||
pTable_ymax | |||
pTable_ysum | |||
pTable_dxmin | |||
pTable_dxmax | |||
pTable_dymin | |||
pTable_dymax |
Source_gen.comp
.
[ Identification | Description | Input parameters | Output parameters | Links ]
Generated automatically by McDoc, Peter Willendrup <peter.willendrup@risoe.dk> / Fri Feb 11 10:12:09 2011