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McStas: Source_pulsed

[ Identification | Description | Input parameters | Links ]

The Source_pulsed Component

A pulsed source for variable proton pulse lenghts

Identification

  • Site:
  • Author: Klaus Lieutenant, based on component 'Moderator' by K. Nielsen, M. Hagen and 'ESS_moderator_long_2001' by K. Lefmann
  • Origin: FZ Juelich
  • Date:

Description

Produces a long pulse spectrum with a wavelength distribution as a sum of up to 3 Maxwellian distributions and one of undermoderated neutrons

It uses the time dependence of long pulses. Short pulses can, however, also be simulated by setting the proton pulse short.

If moderator width and height are given, it assumes a rectangular moderator, and otherwise a circular

Usage example:
Source_pulsed(xwidth=0.04, yheight=0.04, Lmin=1.0, Lmax=3.0, t_min=0.0, t_max=0.5, dist=0.700, focus_xw=0.020, focus_yh=0.020,
freq=96.0, t_pulse=0.000208, T1=325.0, I1=7.6e09, tau1=0.000170, I_um=2.7e08, chi_um=2.5)

Parameters for some sources:
HBS thermal source: xwidth=0.04, yheight=0.04, T1=325.0, I1=0.68e+12/freq, tau1=0.000125, n_mod=10, I_um=2.47e+10/freq, chi_um=2.5, t_pulse=0.016/freq, freq=96.0 or 24.0
HBS cold source   : radius=0.010,              T1= 60.0, I1=1.75e+12/freq, tau2=0.000170, n_mod= 5, I_um=3.82e+10/freq, chi_um=0.9, t_pulse=0.016/freq, freq=24.0 or 96.0
HBS bi-spectral   : radius=0.022, r_i=0.010,   T1= 60.0, I1=1.75e+12/freq, tau2=0.000170,
T2=305.0, I2=0.56e+12/freq, tau1=0.000130, n_mod= 5, I_um=3.82e+10/freq, chi_um=2.5, t_pulse=0.016/freq, freq=24.0 or 96.0

Input parameters

Parameters in boldface are required; the others are optional.
NameUnitDescriptionDefault
xwidthmWidth of the source0.0
yheightmHeight of the source0.0
radiusmOuter radius of the source0.010
r_imRadius of a central circle that is sorrounded by a ring of different temperature0.0
LminAngLower edge of the wavelength distribution
LmaxAngUpper edge of the wavelength distribution
t_minsLower edge of the time interval0.0
t_maxsUpper edge of the time interval0.001
target_index1relative index of component to focus at, e.g. next is +1 this is used to compute 'dist' automatically.1
distmDistance from the source to the target0.0
focus_xwmWidth of the target (= focusing rectangle)0.02
focus_yhmHeight of the target (= focusing rectangle)0.02
freqHzFrequency of pulses
t_pulsesProton pulse length
T1KTemperature of the 1st Maxwellian distribution, for r_i > 0 only for radii r in the range 0 < r < r_i0.0
I11/(cm**2*sr)Flux per solid angle of the 1st Maxwellian distribution (integrated over the whole wavelength range).0.0
tau1sPulse decay constant of the 1st Maxwellian distribution0.000125
T2KTemperature of the 2nd Maxwellian distribution, 0=none, for r_i > 0 only for radii r in the range r_i < r < radius0.0
I21/(cm**2*sr)Flux per solid angle of the 2nd Maxwellian distribution0.0
tau2sPulse decay constant of the 2nd Maxwellian distribution0.0
T3KTemperature of the 3rd Maxwellian distribution, 0=none0.0
I31/(cm**2*sr)Flux per solid angle of the 3rd Maxwellian distribution0.0
tau3sPulse decay constant of the 3rd Maxwellian distribution0.0
n_mod1Ratio of pulse decay constant to pulse ascend constant of moderated neutrons10
I_um1/(cm**2*sr)Flux per solid angle for the under-moderated neutrons0.0
tau_umsPulse decay constant of under-moderated neutrons0.000012
n_um1Ratio of pulse decay constant to pulse ascend constant of under-moderated neutrons5
chi_um1/AngFactor for the wavelength dependence of under-moderated neutrons2.5
kap_um1Scaling factor for the flux of under-moderated neutrons2.2
AT ( , , ) RELATIVE
ROTATED ( , , ) RELATIVE

Links


[ Identification | Description | Input parameters | Links ]

Generated on 2024-01-03 11:47:43


Last Modified: Tuesday, 16-Apr-2024 20:05:21 CEST
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