Low-Energy Muon Facility (LEM)

1. the source of the low-energy muon beam and the low-energy muon beam transport system (the µE4 surface muon beam line, the cryogenic moderator to convert energetic muons to epithermal muons, and a system of electrostatic elements for reacceleration and low-energy muon transport)
2. the low-energy µSR spectrometer (LE-µSR).

See http://lmu.web.psi.ch/docu/nemu/html.

Electronic logbook:

• lem03, web access http://lem03.psi.ch:8000 (PSI intranet only)
• pc12440, elog backup of lem03, readonly, web access http://pc12440.psi.ch:8000 (PSI intranet only)

• location: area mue4
• Positive muons
  • momentum of muE4 beam: 27.7 MeV/c
  • momentum(energy) of low-energy muon beam: 0.45 - 2.5 MeV/c (1 - 30 keV)
  • mean range of low-energy muon beam: 10 - 200 nm
• muE4 muon beam polarization >90%; low-energy muon beam polarization >90%
• Direction of muon spin at sample: -90 - +90° where +90° is in beam direction
• Positron detectors: 8
  • 4 downstream detectors Left/Top/Right/Bottom (with respect to muon momentum)
  • 4 upstream detectors Left/Top/Right/Bottom

• The muon detector, "trigger detector" (TD), about 0.5 m upstream of the sample
• With WEW magnet: eight positron detectors (with respect to the beam direction):
  • Left downstream (LD), histogram 1
  • Top downstream (TD), histogram 2
  • Right downstream (RD), histogram 3
  • Bottom downstream (BD), histogram 4
  • Left upstream (LU), histogram 5
  • Top upstream (TU), histogram 6
  • Right upstream (RU), histogram 7
  • Bottom upstream (BU), histogram 8

• With Bparallel magnet: four positron detectors (with respect to the beam direction):
  • Left downstream (LD), histogram 1
  • Right downstream (RD), histogram 3
  • Left upstream (LU), histogram 5
  • Right upstream (RU), histogram 7

• ExtOff histograms without post-pileup rejection ("npp" histograms), No. 1-8
• ExtOff histograms with post-pileup rejection ("ppc" histograms), No. 9-16
  Use this set of histograms, if background is not fitted but is determined at "negative" times;
  Statistics is reduced by 7-10% compared to npp histograms
• ExtOn histograms without post-pileup rejection ("npp" histograms), No. 17-24
• ExtOn histograms with post-pileup rejection ("ppc" histograms), No. 25-32
  Use this set of histograms, if background is not fitted but is determined at "negative" times;
  Statistics is reduced by 7-10% compared to npp histograms
• histogram identifiers in the original root files:
  • ExtOff npp histograms: IDs 001-008
  • ExtOff ppc histograms: IDs 021-028
  • ExtOn npp histograms: IDs 041-048
  • ExtOn ppc histograms: IDs 061-068

• Konti flow cryostats, 4 - 320 K at sample plate
  • Konti-1: for special experiments (current injection, illumination with LEDs) and tests
  • Konti-2: normal user operation
  • Konti-3: normal user operation, application of electric fields, current injection
  • Konti-4: normal user operation
• lowTemp cryostat:
  • 2.4 - 300 K with sample plate, In coated sapphire
  • 2.2 - 300 K without sample plate; sample directly mounted on sapphire
• Furnace: -50 - 300°C (can be cooled by LN2)
• Sample size:
  • Ideally 25x25 mm² or ∅ = 25 mm
  • mosaic of four pieces of 10x10²mm
  • 10x10 mm² possible, but only 30-50% of muons hitting the sample, depending on implantation energy (30% for 1keV, 50% for zero or negative sample bias)
• Magnets
  • WEW magnet (TF and LF): 0 - 0.34 T parallel to the beam
  • Bparallel magnet (TF and ZF) : 0 - 30 mT, vertical, perpendicular to the beam

• DAQ server: lem00, midas access through http://lem03.psi.ch:8081 (PSI intranet only).
• (backup system: lem00)
• client pc12438, Linux RHEL7 64-bit, for online analysis and experiment control
• client pc12439, Linux RHEL7 64-bit, for online analysis and experiment control

Printers next to LEM counting room:

• WEHA, close to piE5 area
• WBGA

• /mnt/data/nemu/his/, root histogram files
• /mnt/data/nemu/psibin/, psi-bin histogram files

• /mnt/home/nemu/analysis// subdirectories

• /afs/psi.ch/project/nemu/data or
  /afs/psi.ch/project/bulkmusr/data/lem/dYYYY
  where YYYY is the year of the experiment
• /afs/psi.ch/project/nemu/analysis