LET

This page collects information that will be useful for the implementation of the IBEX control system on LET.

Background & Timeline

LET is a cold neutron multi-chopper spectrometer on TS2 at ISIS. The LET web page describes the background to the instrument.

Control System

It is proposed to migrate from the SECI control system to the IBEX control system in time for Cycle 2018/04. LET does currently use IBEX to control its SKF choppers (but that’s all).

LET Equipment

The equipment listed below is used on LET. Please add new information (e.g. new items of equipment, new notes, information about drivers, etc. to this table).

Manufacturer	Model	Type	Connection	Driver	Notes
ISIS	DAE 2	Detector Electronics	Ethernet		see DAE note
SKF	MB4150-G5	Disk Chopper	Ethernet		see High-Speed SKF Disk Chopper note
Astrium	TBD	Disk Chopper	TBD	.NET	see High-Speed Astrium Disk Chopper note
ISIS	Mk3	Disk Chopper	Ethernet	.NET	see ISIS Chopper note
N/A	N/A	Jaws			see Jaws note
Pfeiffer	TPG300	ISIS Vacuum System	RS232	#216	see Pfeiffer note
Eurotherm	Temperature Controller	All models at ISIS	RS-232	EPICS	see Eurotherm note
ISIS	Orange Cryostat	Cryogenic System	RS-232		see Orange Cryostat note
Oxford Instruments	Heliox	Dilution Fridge	RS-232	#3739	see Oxford Instruments note
Oxford Instruments	Triton	Dilution Fridge	RS-232	#2744	see Oxford Instruments note
ISIS	???	Mezei Flipper		#3738	see Mezei Flipper Notes
ISIS	Furnace	High temperature furnace	RS-232		see Furnace note
Oxford Instruments	9T	Magnet	???	#2765	see 9T Magnet note
Oxford Instruments	14T	Magnet	???		see 14T Magnet note
Lakeshore	340	Temperature Controller	RS-232	EPICS	see Lakeshore note
ISIS	ORC	Collimator	via Galil	#2535	see LET Notes
ISIS	McLennan	Sample Changer	via Galil		see LET Notes
ISIS	McLennan	Rotation Stage	via McLennan		see LET Notes
ISIS	McLennan-Newport	Rotation Stage	via McLennan		see LET Notes

Note: DAE

Main Detector banks + several fixed monitors.

Note: High-Speed SKF Disk Chopper

LET currently has 2 high-speed SKF choppers (same as IMAT). These are currently controlled using a mini-IBEX system.

1. SKF G5 choppers also used on IMAT (see #1907).

   • SKF MB4150-G5 Chopper

   • MBScope software for SKF magnetic bearing choppers.

Note: High-Speed Astrium Disk Chopper

LET currently has 2 high-speed Astrium choppers. These are due to be replaced by 2 new SKF G5 choppers ~within 9-12 months (from September 2017).~ Latest news: The Astrium choppers will be replaced in early 2020 ~(one might even be replaced as early as August 2019).~, but more likely is chopper 5 in January/February shutdown and chopper 1 in the long shutdown.

The Astrium choppers are currently controlled by 2 VMs running on NDHLET (one VM per chopper). The VMs communicate with the choppers, via a MOXA, using a .NET connection.

Note: ISIS Disk Chopper

LET currently has 1 Mk3 ISIS chopper.

Note: Jaws

LET has no jaws.

Note: Pfeiffer

Model TPG 300, used for vacuum system read-back.

Note: Eurotherm

Eurotherms in use on LET. Used to control temperature of all top-loading CCRs, Orange cryostats, heaters and furnaces.

Note: Lakeshore

NOTE: this entry added 07-02-2019.
LET uses a Lakeshore Model 340 cryogenic temperature controller.

1. Model 340.

   • According to the Lakeshore web-site, the Model 340 is now obsolete. It has been replaced by the models 336 and 350.

Note: Orange Cryostat

Controlled via Eurotherm.

Note: Oxford Instruments

1. Dilution fridges: models. LET uses both Triton and Heliox dilution fridges

   • Triton

     • Triton LabVIEW Driver : C:\LabVIEW Modules\Drivers\Triton

     • Triton Documentation : C:\LabVIEW Modules\Drivers\Triton\Documentation

     • See also #2915

   • Heliox

     • The Heliox dilution fridge is currently (November 2018) broken and is being repaired at Oxford Instruments. There is no ETA on when it will be fixed. There are no experiments scheduled to use the Heliox dilution fridge. Obviously, that will change when the Heliox is repaired.

Note: ISIS 9T Chopper Magnet

ISIS 9T Chopper Magnet See also:IBEX Support for 9T chopper magnet.

Note: ISIS 14T Magnet

LET has, in the past, used the ISIS 14T Magnet. This magnet is currently being repaired and there is no ETA on when it might return to service.

Note: Mezei Neutron Spin Flipper

The Mezei Neutron Spin Flipper is a collection of devices (power supplies, signal generators & control PC) housed in a mobile rack. The control PC runs a Python script to control the power supplies & signal generators. The Python script accepts a set of simple commands. The Mezei Neutron Spin Flipper is, at the time of writing, used on LET and POLREF. In future, it may be used on other instruments too.

There is a VI to control the PSU, located here: C:\LabVIEW Modules\Instruments\POLREF\POLREF Flipper. It was originally developed by Gareth Howells, but has subsequently been modified by students. Consult with Goran Nilsson & Andrew Caruana for more details.

N.B.: LET plans to use this device in Cycle 2018/04.

Note: ISIS High temperature furnace

Controlled via Eurotherm. Furnaces are used only very rarely on LET.

LET Notes

LET has the following specialist systems:

1. LET specific oscillating radial collimator. Controlled by special program downloaded into Galil.

   1. See 2535

2. LET sample changer

   • A sample changer has not often been used on LET. From Cycle 2018/04 LET will be using a sample changer of the same design as the MERLIN sample changer (the two devices should be interchangeable).

3. LET rotation stage

   • LET has two rotation stages;

   1. A McLennan rotation stage (same as MERLIN, used with CCRs & Orange Cryostats))

   2. A McLennan-Newport rotation stage (used with the 9T Magnet)

LET SECI Configs

LET has a number of SECI configurations. Equivalent IBEX configs for the following combinations of equipment are required:

• Eurotherm (for Cryostat or CCR) + rotation stage

• Eurotherm (for Cryostat or CCR) + ORC + rotation stage

• Eurotherm (for Cryostat or CCR) + dilution fridge (Triton) + rotation stage

• Eurotherm (for Cryostat or CCR) + dilution fridge (Triton)+ ORC + rotation stage

• Eurotherm (for Cryostat or CCR) + dilution fridge (Heliox) + rotation stage

• Eurotherm (for Cryostat or CCR) + dilution fridge (Heliox)+ ORC + rotation stage

• 9T Magnet + McLennan-Newport rotation stage

LET Genie Scripts

LET has a number of instrument specific Genie scripts. The key scripts to be migrated to genie_python are:

Script	Purpose	Notes
park_choppers	It parks the choppers, of course	Needed because LET has 4 choppers
set_ei5	Sets chopper speed/phase	This is the LET version of set_ei. It is not the same as set_ei used on other excitations instruments. It would be helpful if set_ei5 could be extended to better support vetoes and wiring tables. Ignore the older versions set_ei1 - set_ei4.
mono

On LET user scripts are usually created by modifying an old user script. Create a template genie_python script (based on an old user script) which can be used in future.