IN5
Disk chopper time-of-flight spectrometer
ILL7 building, Cold neutron guide H16 |
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(Vertical Cold Source) |
Monochromatisation | |
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6 counter-rotating choppers | |
Chopper velocity Vo | 2000 rpm to 17000 rpm |
Incident wavelength λo | 1.8 Å to 20 Å |
Sample | |
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elastic energy resolution | ~ 100 µeV |
max neutron energy loss |
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max energy gain for the neutrons | Emax ~ ∞ . . . |
max momentum transfer Qmax | 11.48/λo Å-1 |
horizontal divergence (no collim.) | ~ 0.1×2×λo [°] |
vertical divergence (no collim.) | ~ 0.1×3×λo [°] |
Collimation before sample | - / 30' / 60' |
beam size at the sample | ~ 15×50 mm2 |
flux at the sample at 5.0 Å | 6.83×105 [n/cm2/s] |
ωmax 0.6×EoDetectors | |
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detector shape | cylindrical |
detector surface [m2] | 30.0 |
fight path (radius of reading) [m] | 4.0 |
effective detection height [m] | 3.0 |
scattering angular range [°] | -12° to 135° |
vertical angular range [°]e | ±20.55° |
solid angle covered | 1.8 sr (~0.6π) |
min. & max. momentum transfer [Å-1] | 0.2/λ [Å] - 11.8/λ [Å] |
spatial resolution [cm2] | 2.6 x 2.6 |
angular resolution [° / rad / '] | 0.37° / 6.10-3 rad / 22 |
detector type | position sensitive 3He counters |
gas mixture | 4.75 bar 3He +1.25 bar CF4 |
detector efficiency | ~ 80% for Eo = 3.27 meV (5 Å) |
dead time / max. count rate (per tube) | ≤ 10 µs / ≥ 100 kHz |
material | stainless steel |
number of detectors units (32 tubes/unit) | 12 |
tubes diameters [inches/cm] | 1' / 2.54 |
Acquisition | |
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nb. of pixels per tube / per unit / total | 256 / 8192 / ~105 |
time channel / pixel | ≤ 1024 |
max. raw data volume / spectrum | ≤ 768 Mb |
Sample environment | |
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accommodating samples with 69 mm Ø | |
dilution fridge (LT1) | ≤ 50mK ... 1.6K |
vertical cryomagnet S(MV) | 0 ... 2.5 Tesla and 0 ... 10 Tesla |
ILL orange cryostat (CO) | 1.5 ... 310 K |
cryofurnace (CF) | 2.5 ... 600 K |
furnace (F2) | 300 ... 1600 °C |
heating and cooling loop (CL) | 100 ... 620 K |
Instrument description
IN5 is a general purpose direct geometry Time of Flight (ToF) spectrometer. It is used to study low-energy transfer processes as a function of momentum transfer. Typically this instrument is used for measurements in the small energy and momentum transfer region with values of the order of δE/E = 1 % for the energy resolution (e.g. quasi-elastic scattering in solids, liquids, molecular crystals and inelastic scattering with small energy transfers in the order of magnitude 0.1 - 250 meV). It offers total flexibility of wavelength selection and chopper speed which permits considerable optimisation of the energy range, energy resolution, momentum-transfer range and countrate.
Primary spectrometer:
the chopper system provides an extremely well defined resolution function which remains nearly gaussian (counter-rotating disks) down to 1/10 000 of its height.
Secondary spectrometer:
it consists in an large cylindrical array of pixelated position sensitive detector (PSD) mounted inside a vacuum time-of-flight chamber 4m from the sample. PSDs cover a large gapless detection surface (30m2) with a spatial resolution comparable to triple-axis instruments. With the new detector, the instrument has a large solid-angle for powder and amorphous systems experiments and is fully equipped for single-crystal spectroscopy.
Sample area:
a large sample chamber (max diameter = 80cm, depth ~ 130cm) allows hosting the broad range of IN5 sample environments but also user-designed equipments (contact instrument responsibles before). The non-magnetic material surrounding the sample allows the use of either high magnetic field (limited to 2.5T at the moment it is foreseen to purchase a specific magnet for higher fields - equal or above 10T) or neutron polarisation devices (still to come).