ORaNGE

Optically readout GEM

The high-resolution tracking of low energy release particles had a remarkable development in recent years and will give a crucial contribution in different sectors, from medical applications to dark matter search.
Thanks to their characteristics (high space and time resolution, low material budget, large volumes, low costs) Time Projection Chambers based on Micro Pattern Gas Detectors gas detectors have shown to be ideal candidates for this devices.
A very promising technique is represented by the optical readout of the light produced by the de-excitation of gas molecules during the processes of electron multiplication.It is possible to obtain very high perfomance by this technique, exploiting the great progresses achieved in micro pattern gas detectors and in the evolution of the CMOS technology which led to the production of sensors offering high sensitivity and granularity combined with a very low noise level.

Fig 1: the ORANGE prototype equipped with a triple 10x10 cm2 GEM

Fig 2: One of the first images of cosmic muon acquired in the 2015 with the first prototype having a 1 cm high sensitive gap, readout by a triple 10x10 cm2 GEM structure

Fig 3: track of a low energy electron due to natural radioactivity

Fig 4: ORANGE detector installed at the beam test Facility of Frascati

• In 2017 a larger prototype (Large Elliptical Module Optically Readout: “LEMOn”) with a 7 litre sensitive volume was built and tested.

Fig 1: LEMON prototype elliptical field cage and 20*24 cm LHCb type GEM readout system

Fig 2: tracks due natural radioactivity and cosmic rays “seen” in a 5 seconds time interval by the detector. The elliptical shape (20 cm and 24 cm long axes) of the drift field cage is well visible

Fig 3: an alpha particle releases the whole its energy in detector before being captured.

Fig.4: shows a 20 cm long cosmic muon track

Fig 5: the LEMON prototype installed at the Frascati Beam Test Facility (BTF)

Fig.6 shows a 24 cm long track of a 450 MeV electron acquired at the BTF

Reference:

• High granularity tracker based on a Triple-GEM optically read by a CMOS-based camera
• EPS2017:  CYGNUS : DEVELOPMENT OF AHIGH RESOLUTION TPC FOR RARE EVENTS
• RD51 Collaboration Meeting, CERN:
  • https://www.dropbox.com/s/dfn38iuqsuqjkxe/presentation_Dec16.pdf?dl=0
  • https://www.dropbox.com/s/6kigjysoadgyf4k/1508.07143.pdf?dl=0
  • https://www.dropbox.com/s/lkrs0ww172rqnxr/pinci_proceeding.pdf?dl=0