IN16B

Versatile high flux backscattering spectrometer

Guide hall nº1, cold neutron guide H112
beam size at sample	30 x 30 mm² (smaller for BATS t.b.d.)

Sample environment
cryofurnace (50 mm); max. sample diameter 48 mm	1.8 K - 560 K
cryostat (70 mm); max. sample diameter 68 mm	1.5 K - 320K
furnace	300 - 1300 K
vacbox 70mm - highly variable housing with outer dimension of orange cryostat with narrow tail; various vacuum tight connectors and feed through adaptable for your needs (to be prepared in time with an instrument responsible)	no temperature control foreseen yet, but possible near RT
no windows to secondary spectrometer which is typically in vacuum (ONLY if no risk of sample leakage! breaking & re-pumping of vacuum 1-2 hours) or otionally in air.

Characteristics

IN16B is on H112

efficient optics with ballistic neutron guide
two main configurations:
- 'high flux' (HF) at guide end position or
- 'low background' (LB) at guide side position
band width selection with selector and additional PG(002) deflector in LB configuration
flux gain through Phase Space Transformation (PST) chopper
more solid angle by new taller analysers
wider dynamic range through new Doppler linear motor drive and PST
lower background through background chopper and vacuum housing
secondary spectrometer can be operated alternatively without vacuum
several Doppler velocity profiles (sine, constant velocity)

change over times for configurations:

Change-over times between different configurations are long and if possible will be scheduled for a full or half cycles only. As an example the change from HF to LB configuration or back including alignment needs several days and the change between different monochromator/analyser configurations including alignment needs about 2 days.

detectors
standard: PSD multidetector array (16 tubes with vertical position sensitivity) + 2 ³He counters + 1 monitor alternatively: up to 8 ³He single counters and no PSD For diffraction: PSD's (in progress)

Instrument configurations
	Si(111)		Si(311)	GaAs(200)	BATS
	standard E-resolution	high E-resolution	access to high Q with high E-resolution	best E-resolution	wide E-transfer range
monochromator	Si111	Si111 polished	Si311	GaAs200 (first prototype commissioning 2017; to be continued end 2018)	TOF-backscattering chopper cascade & selector (commissioning ongoing)
incident wavelength (Å)	6.271	6.271	3.275	5.654	dlambda/lambda ~12%
incident energy (meV)	2.08	2.08	7.63	2.56
flux at the sample (n/cm²/s) @ 58 MW	HF: 6.0 10⁵ LB: 8.7 10⁴	t.b.d.	HF: 1.2e5	t.b.d., but sensibly lower than Si(111)	t.b.d.
analysers	Si(111): small angle & arc analysers of old IN16 type; 6 new tall Large Angle Analysers (LAAs)	Si(111) polished: small angle & arc analysers + only 3 old IN16 type LAAs (half height ±19°)	Si(311): NO small angle & NO arc analysers; only 6 old IN16 type LAAs (half height ±19°)	GaAs(200) ~ 0.3 m² test analyser	Si(111) or Si(311)
energy resolution (μeV)	∼0.75	∼0.30 (~0.5 SANS)	∼ 2.0	reached ~ 75 neV in first commissioning March 2017	~ 1.5 - 8
energy transfer (μeV)	±31	±31	±59	t.b.d.,	~ ± 250 / ±70 / -850...1000 for Si(111) / Si(111) high rep. rate / Si(311)
Q-range (Å^-1)	0.1 - 1.8	0.1 - 1.8	0.7 - 3.5	t.b.d.	~ 0.2 - 1.8
comments	high flux (HF) standard position NEW: choose chopper ratio 1:1 for 'high flux' or 2:1 for 'high signal-to-noise' (HSNR-mode) low background position (LB) commissioned available only if well justified (consider HSNR instead)	commissioned in HF position monochromator now available	commissioned in HF position be aware of Bragg contaminations from sample holder and cryostats be aware of low flux foresee delay in scheduling as accepted experiments need to be grouped into one cycle	German Verbundforschungs-project of FAU-Erlangen & ILL - financed by the German ministry BMBF (July 2013 - July 2019) commissioning of a reduced surface analyser and monochromator done in cycle 171 prototyping - not yet aimed for user operation	German Verbundforschungs-project of FAU-Erlangen & ILL - financed by the German ministry BMBF (July 2013 - July 2019) in user operation