[ Identification | Description | Input parameters | Links ]
Source_gen4 Component
This 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). And a high energytail of the shape A/(lambda0-lambda) can also be
specified if you give an A. 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 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, 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= 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. NO correction for solid-angle is applied, the intensity emitted into the chosen xw x yh rectangle at distance dist. | 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) | 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 divergence 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 | |
| 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) | Second Maxwellian Source flux | 0 | |
| T3 | K | Third Maxwellian source Temperature, 0=none | 0 | |
| I3 | 1/(cm**2*st) | Third Maxwellian Source flux | 0 | |
| length | m | Source z-length, not anymore flat | 0 | |
| phi_init | degrees | Angle abowe the x-z-plan that the source is amied at | 0 | |
| theta_init | degrees | Angle from the z-axis in the x-z-plan that the source is amied at | 0 | |
| HEtailA | 1/(cm**2*st*AA) | Amplitude of heigh energy tail | 0 | |
| HEtailL0 | AA | Offset of heigh energy tail | 0 |
| AT ( | , | , | ) RELATIVE | |||
|---|---|---|---|---|---|---|
| ROTATED ( | , | , | ) RELATIVE |
Source_gen4.comp.
[ Identification | Description | Input parameters | Links ]
Generated on 2024-01-03 11:47:43