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McStas: Source_pulsed Component

[ Identification | Description | Input parameters | Output parameters | Links ]

The Source_pulsed Component

Date : Aug 2020 A pulsed source for variable proton pulse lenghts

Identification

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

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

WARNING: This is a contributed Component.

Input parameters

Parameters in boldface are required; the others are optional.
Name Unit Description Default
xwidth m Width of the source 0.0
yheight m Height of the source 0.0
radius m Outer radius of the source 0.010
r_i m Radius of a central circle that is sorrounded by a ring of different temperature 0.0
Lmin Ang Lower edge of the wavelength distribution  
Lmax Ang Upper edge of the wavelength distribution  
t_min s Lower edge of the time interval 0.0
t_max s Upper edge of the time interval 0.001
target_index 1 relative index of component to focus at, e.g. next is +1 this is used to compute 'dist' automatically. 1
dist m Distance from the source to the target 0.0
focus_xw = focusing rectangle [m] Width of the target 0.02
focus_yh = focusing rectangle [m] Height of the target 0.02
freq Hz Frequency of pulses  
t_pulse s Proton pulse length  
T1 K Temperature of the 1st Maxwellian distribution, for r_i > 0 only for radii r in the range 0 < r < r_i 0.0
I1 1/(cm**2*sr) Flux per solid angle of the 1st Maxwellian distribution (integrated over the whole wavelength range). 0.0
tau1 s Pulse decay constant of the 1st Maxwellian distribution 0.000125
T2 K Temperature of the 2nd Maxwellian distribution, 0=none, for r_i > 0 only for radii r in the range r_i < r < radius 0.0
I2 1/(cm**2*sr) Flux per solid angle of the 2nd Maxwellian distribution 0.0
tau2 s Pulse decay constant of the 2nd Maxwellian distribution 0.0
T3 K Temperature of the 3rd Maxwellian distribution, 0=none 0.0
I3 1/(cm**2*sr) Flux per solid angle of the 3rd Maxwellian distribution 0.0
tau3 s Pulse decay constant of the 3rd Maxwellian distribution 0.0
n_mod 1 Ratio of pulse decay constant to pulse ascend constant of moderated neutrons 10
I_um 1/(cm**2*sr) Flux per solid angle for the under-moderated neutrons 0.0
tau_um s Pulse decay constant of under-moderated neutrons 0.000012
n_um 1 Ratio of pulse decay constant to pulse ascend constant of under-moderated neutrons 5
chi_um 1/Ang Factor for the wavelength dependence of under-moderated neutrons 2.5
kap_um 1 Scaling factor for the flux of under-moderated neutrons 2.2

Output parameters

Name Unit Description Default
area  
t_period  
alpha  
p_in  

Links


[ Identification | Description | Input parameters | Output parameters | Links ]

Generated automatically by McDoc, Peter Willendrup <peter.willendrup@risoe.dk> / Fri Sep 23 18:47:27 2022


Last Modified: Friday, 23-Sep-2022 20:47:27 CEST
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