[ Identification | Description | Input parameters | Links ]

The ESS_IN5_reprate Instrument

An IN5 type (cold chopper) multi-frame spectrometer at ESS LPTS

Identification

• Site: ESS
• Author: Kim Lefmann (kim.lefmann@risoe.dk), Helmuth Schober, Feri Mezei
• Origin: ESS
• Date: September 20, 2006

Description

McStas instrument for simulating IN5-TYPE (cold chopper) multi-frame spectrometer at ESS LPTS.
The sample is incoherent with an inelastic tunneling line.

Input parameters

Parameters in boldface are required; the others are optional.

Name	Unit	Description	Default
Lmin	AA	Minimum wavelength emitted by the moderator	4.9
Lmax	AA	Maximum wavelength emitted by the moderator	5.1
lambda0	AA	Target wavelength for the monochromating crystal	5
Pulse_width	s	Length of the long pulse. Default to 2 ms.	2.857e-3
Num_pulses	1	Number of pulses to simulate. Default 1.	1
GUI_start	m	Distance from moderator to guide start	2.0
FO1_DIST	m	Distance from moderator to FO1 chopper	6
L_ballistic_begin	m	Length of expanding ballistic section in the beginning of the guide	19.5
L_ballistic_end	m	Length of compressing ballistic section in the end of the guide	17
Length	m	Total length of spectrometer (moderator to F2)	100
SAMPLE_DIST	m	Distance from F2 to sample	1.2
DETECTOR_DIST	m	Length sample-detector	4
GUI_h	m	Height of guide opening at entry	0.105
GUI_w	m	Width of guide opening at entry	0.1
GUI_GAP	m	Gap between guides due to chopper hardware	0.05
H1	m	Height of guide elements	0.167
W1	m	Width of guide elements	0.116
H2	m	Height of guide elements	0.185
W2	m	Width of guide elements	0.15
H3	m	Height of guide elements	0.19
W3	m	Width of guide elements	0.15
H4	m	Height of guide elements	0.213
W4	m	Width of guide elements	0.14
H_chop	m	Height at F2 chopper position	0.075
W_chop	m	Width at F2 chopper position	0.03
H_end	m	Height of guide opening at exit	0.042
W_end	m	Width of guide opening at exit	0.0215
ALPHA	m	Parameter for supermirrors in guides, Swiss Neutronics best at 3.4	3.4
M	1	Parameter for supermirrors in guides, Swiss Neutronics best at 4	3.5
F_slow1	Hz	Frequency of the FO1 chopper	16.6667
F_slow2	Hz	Frequency of the FO2 chopper	0
F_fast1	Hz	Frequency of the F1 chopper	0
F_fast2	Hz	Frequency of the F2 chopper	200
N_fast	1	Number of symmetric openings in the fast F choppers	1
SLOW1_THETA	deg	Opening angle of the FO1 chopper	120
FO3	1	Inverse frequency of FO3 chopper (if 1, same as F2; if 2, half of F2, etc.)	1
THETA_fast1	deg	Opening angle of the F1 chopper	180
FAST_THETA	deg	Opening angle of the F2 chopper	5
Gamma	meV	Width of sample quasielastic scattering (0=elastic)	0
Etun	meV	Tunneling energy	1
V_HOLE	m	Radius of hole in V sample (must be smaller than the outer radius: 0.01)	0
FRAC_QUASIEL	1	Fraction of the sample that scatters quasielastically	0
FRAC_TUNNEL		Fraction of the sample that scatters on the tunneling peaks	0
TT	deg	2Theta (or a4) scattering angle	50
RES_DE	meV	Adjustable zoom for energy monitor at detector position	0.5
cold		Fraction of neutrons emitted from the cold moderatorx	0.95

Links

• Source code for ESS_IN5_reprate.instr.
• The ESS-Rencurel website.
• The IN5@ILL Yellow Pages

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[ Identification | Description | Input parameters | Links ]

Generated for mcstas 3.5.32

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Last Modified: Monday, 30-Jun-2025 11:05:10 CEST