MARI technical specification

Schematic of the MARI detector bank

Schematic of the MARI detector bank
View full-size image

The following table gives the instrumetal parameters and available energy resolutions and fluxes on MARI

Moderator

liquid-methane (CH4) at 105K (poisoned with Gd at 2.5 cm)

Incident energy

7 - 1000 meV

Energy resolution

Depends on the choice of Fermi chopper, incident energy and energy transfer

 D hw /Ei  = 1.5-8 % 

Primary flight path

11.739 m

Secondary flight path

4.020 m

Fermi Chopper

10.050 m

50-600 Hz phased to ISIS pulse ±  0.1 μs

4 chopper packages are commonly used on MARI optimised for different incident energy and resolution requirements

  • G-Chopper - Gd slits,     7-200 meV,      ΔE/Ei 2-5%
  • S-Chopper - "Sloppy",    7-1000 meV,    ΔE/Ei 3-8%
  • A-Chopper - "High res", 100-1000 meV, ΔE/Ei 1.5-3%
  • R-Chopper - "Relaxed", 200-1000 meV, ΔE/Ei 2-7%
Detectors

Low Angle Bank

4.020 m from sample 256 10 atm 3He tubes in 8 fold array covering 3 - 13º scattering angle

High Angle Bank

4.020 m from sample 10 atm 3He tubes covering 12º - 135º scattering angle

Monitors

Monitor 1: 07.000 m from moderator
Monitor 2: 10.297 m from moderator
Monitor 3: 17.559 m from moderator

Flux at Sample

[× 104 n cm-2 s-1]  

 7 meV25 meV100 meV500 meV
G-Chopper 4% ΔE/E0.5 1.4 0.9n/a
S-Chopper 5% ΔE/E0.51.50.91.3
A-Chopper 2.5% ΔE/En/an/a 0.30.4
R-Chopper 4% ΔE/En/a0.80.50.7
Bookmark and Share
Skip to the top of the page