HFBS sample environment equipment

National Institute of Standards and Technology

HFBS: sample environment

The geometry of the backscattering spectrometer is such that the equipment from the general sample environment pool are not necessarily compatible with the instrument. We have a dedicated set of equipment that covers most of the conditions required by those who perform experiments on the HFBS. If you are unsure whether your experimental requirements can be met, or if you have special requirements, please contact one of the instrument responsibles.

Additional information provided by the NCNR sample environment team can be found by visiting their webpage.

Equipment

	Cryostat	Closed cycle refrigerator	Furnace

Temperature range (K)	1.7 to 300	4 to 325	300 to 1700
		50 to 600
Maximum sample can diameter (mm)	45	68	30
Maximum sample can length (mm)	160	180	160
Mounting hardware (length = 7 mm)	M8 or 5-16/18 stud	M8 or 5-16/18 stud	M8 stud
Mount-beam center distance (mm)	0 - 80	15, 35, 48, 60	0 - 80
Gas handling (1/8'' stainless steel tube)	Yes	Yes	No

Sample cans

The sample cans that are generally used on the HFBS are made of aluminum and are sized to be commensurate with the neutron beam dimensions. These cans can be sealed with either indium or lead o-rings, depending on the temperature range desired. A drawing of the cans and one of the inserts is shown below.

Drawing of the sample can and lid used on the HFBS

Experiments that access temperatures in excess of 800 K cannot use aluminum cans. For these measurements, some appropriate can materials are niobium and platinum. We have a limited number of such cans available, but please be sure to coordinate with one of the instrument responsibles to plan your experiment, as there are some other special requirements involving the furnace.

Sample can mounting information

Top-loading Closed Cycle Refrigerator (CCR)

The Top-loading Closed Cycle refrigerator is the default sample environment on HFBS since it is the most commonly used. It is a top-loading version of the well known CCR (aka displex- see description below). The sample is placed at the bottom of the stick and then inserted into the sample well.

Link to the closed-cycle refrigerators website.
Link to the top-loading CCR manual.

Cryostat

The HFBS cryostat is a 50 mm ILL-style cryostat with a specially designed tail-set to fit into the sample space on the spectrometer. It is equipped with a gas fill line that can be attached to your sample holder.

Link to the cryostat website.
Link to the cryostat manual.

Closed cycle refrigerator (CCR)

The CCR (aka displex) is mounted into an aluminum bucket we call the "top hat" and then lowered into the sample pit on the HFBS. Depending on the particular CCR that is used, it may be necessary to use spacers between the CCR flange and the top hat. The distance to the beam center as measured from the bottom surface of the top hat (as indicated in the diagram to the left) is 141.3 mm. A gas fill line can be installed on the CCR.

Link to the closed-cycle refrigerators website.
Link to the general use CCR manual.

Furnace

The HFBS has a dedicated furnace with a 30 mm sample well. Please note that this is narrower than the standard 50 mm well. In addition, the geometry of the well, with a very long insert stick, imposes an additional constraint on the sample can. It is crucial that the sample be contained within a cylinder of diameter 30 mm concentric with the sample stick after it is mounted in the furnace. Please be sure to contact us if you intend to use the furnace on HFBS.

Link to the furnace website.
Link to the HFBS furnace manual.

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Last modified 25-April-2008