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

# The `ESS_IN5_reprate` Instrument

## Identification

- Site: ESS
- Author: Kim Lefmann (kim.lefmann@risoe.dk), Helmuth Schober, Feri Mezei
- Origin:ESS
- Date: September 20, 2006
- Version: 1.3

## Description

    McStas instrument for simulating IN5-TYPE (cold chopper) multi-frame spectrometer at ESS LPTS

## Input parameters

Parameters in boldface are required; the others are optional.

Name | Unit | Description | Default
--- | --- | --- | ---
Lam_min | AA | Minimum wavelength emitted by the moderator | 4.9
Lam_max | AA | Maximum wavelength emitted by the moderator | 5.1
Lam_target | AA | Target wavelength for the monochromating crystal | 5
Pulse_width | s | Length of the long pulse. Default to 2 ms. | 0.002
Twopulses | 1 | Possibility of emitting neutrons from a second pulse. Default 0. | 0
GUI_start | m | Distance from moderator to guide start | 1.5
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 | moderator to F2 | [m] Total length of spectrometer | 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 H1-H4: [m] Height of guide elements W1-W4: [m] Width of guide elements | 0.1
GUI_GAP | m | Gap between guides due to chopper hardware | 0.05
H1 |  |  | 0.167
W1 |  |  | 0.116
H2 |  |  | 0.185
W2 |  |  | 0.15
H3 |  |  | 0.19
W3 |  |  | 0.15
H4 |  |  | 0.213
W4 |  |  | 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 | if 1, same as F2; if 2, half of F2, etc. | [1] Inverse frequency of FO3 chopper | 1
THETA_fast1 | deg | Opening angle of the F1 chopper | 180
FAST_THETA | deg | Opening angle of the F2 chopper | 5
Gamma | 0=elastic | [meV] Width of sample quasielastic scattering | 0
Etun | meV | Tunneling energy | 1
V_HOLE | m | Radius of hole in V sample (must be smaller than the outer radius: 0.01) FRAC_QUASIEL [1] Fraction of the sample that scatters quasielastically | 0
FRAC_QUASIEL |  |  | 0
FRAC_TUNNEL |  |  | 0
TT | deg | 2T (or a4) scattering angle | 50
RES_DE | meV | Adjustable zoom for energy monitor at detector position | 0.5

## Links

- Source code for `ESS_IN5_reprate.instr`.
- The ESS-Rencurel website.

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