[ 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.

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	m	Width of the target (= focusing rectangle)	0.02
focus_yh	m	Height of the target (= focusing rectangle)	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

AT (	,	,		) RELATIVE		Generate
ROTATED (	,	,		) RELATIVE

Links

• Source code for Source_pulsed.comp.

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[ Identification | Description | Input parameters | Links ]

Generated on 2025-05-08 13:31:31

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Last Modified: Monday, 30-Jun-2025 11:05:11 CEST