Low Temperature Facility Instrument (LTF)

General Specifications

  • Location: area piM3.3
  • Positive muons, momentum 5-30MeV/c (Standard: 28MeV/c)
  • Polarization >95%
  • Direction of spin ~ 0-50deg with respect to muon momentum
  • Positron Detectors: 4
  • Main Magnetic Field: 0 - 2.8T (3.0T on request) parallel to the beam
  • Auxiliary Field: 0-10mT perpendicular to the beam
  • Temperature Range: 11.3mK -10K

Earth-field compensation is usually better than 0.001mT for all directions. Some variation (±0.002mT) can occur depending on the position of the 60-ton crane in the hall. Stray field from Quadrapole Focus Magnets QSL302/QSE304 at the sample position (+9mG)

Detector Arrangement

The detector arrangement consists of a single Muon (M) Trigger detector and four positrons detectors. M | Backward (left .OR. right) | Forward (left .OR. right) | Left | Right

Sample Environment


The instrument LTF is equipped with a top-loading 3He-4He DR cryostat which can reach down to about 0.02K.

The cryostat has basically two modes of operation (i.e. Mixture IN or Mixture OUT). In the Mixture IN mode, the highest achievable temperature is limited to about 0.8K. In the Mixture OUT mode, the lowest achievable temperature is limited to about 0.9K. Note that the changeover between these two modes requires a number of manual operations performed by the instrument scientist and it is rather time consuming. A careful planning of the beamtime should therefore be performed, possibly after discussions with the instrument scientist.


Sample sizes should be no bigger than 22 * 12 * 3.5mm.

Users should arrive early enough prior their beamtime to allow the gluing of the samples. This should be done after discussing with the instrument scientist.

Those users wishing to have their samples positioned and glued before arriving at PSI can find the dimensions of Silver plates and Masks suitable for attaching to the Silver LTF_Sample Holders below. Please discuss first with the instrument scientist.
(Reference : The Silver mask has a mylar "window" 18*10mm.
The "M" counter window measures 14*8mm )
  • LTF_Sample Holder Mask (Sample Size : 22*12*3.5mm)
    PDF format (52 kb : A3)
  • LTF_Sample plate (Rec.dimensions : 34*13.5*0.5mm)
    PDF format (35 kb : A3 )

Electronics / Data Aquisition

Data Format and Storage

The users are responsible to store in a safe place their own data. Every week a backup of the data is performed in the PSI Archive system and the specific muSR ftp-server (see here for more information).


The new TDC electronics is characterized by a logic performed exclusively at the software level. A manual is available in PDF format.


The area is equipped with a Experiment Console (running Scientific Linux) pc9627. The µSR data acquisition system hardware consists of this console and a Linux back-end server (psw414) located in the computing building (Hauptgebäude). This back-end is connected to a PC (PC12024) controlling the VME TDC electronics. A number of different devices (temperature controllers, magnetic field power supplies, etc...) are used for the slow control of the experiment. These devices are mainly controlled via GPIB (IEEE-488) bus or RS-232 serial line.
The GPIB devices are controlled through Agilent LAN/GPIB Gateways (E5810A).
The RS-232 devices are controlled through either a Moxa Nport 5150 which supports one RS-232 line, or a Lantronix ETS8PS 8-channel RS232 terminal server.

The acquisition software deltat is based entirely on the DAQ software package MIDAS.

A Linux Workstation (pc8578) is also available and can be used through a usual AFS account or a local account (ask the instrument scientist for information). From this machine, one can connect also to the Linux cluster.

The HIPA secondary beam-line control system controls the beam-line elements (magnets, slit systems, etc.) between the target and the experiments. For the GPS and the LTF instrument the area is equipped with an EPICS Console (hipa-pim3) located in the GPS counting room to set the EPICS Process Variables of the beam-line elements, to optimize beam settings and to diagnose.


Information about how to print at PSI is available here. The nearest printer is WEHA_PIM3_1 on the passage between the GPS counting room and the LTF barrack. There is another color printer located in the blue cabin near the piE5 area named weha_e5_2. This printer also equipped with a copying machine.