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µ M egas used at n_TOF

µ M egas used at n_TOF. µMGAS principles. µMGAS is a two stage ionization chamber (improved version of a ionization with frish - grid) 1 st : ionization&drift (low field) 2 nd : amplification (high field) Converted needed to ionize the gas ( n, a ) 10 B, 6 Li

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µ M egas used at n_TOF

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  1. µMegas used at n_TOF

  2. µMGAS principles • µMGAS is a two stage ionization chamber (improved version of a ionization with frish-grid) • 1st : ionization&drift (low field) • 2nd : amplification (high field) • Converted needed to ionize the gas • (n,a) 10B, 6Li • Elastic recoil in the foil or in the gas • (n,f) 235U or any other fissioning nuclide

  3. µMGAS advantages • Thanks to its two stages µMGAS is a very versatile detector. • By playing on the applied voltages can be sensitive from X-ray to fission fragments • Gas mixture can also enhanced or diminish sensitivity to some particles: • Gas easily available at CERN: • Ar + 10%CF4 + 2%iCH4 (fast, and good resolution) • He + 2% iCH4 (slower, not so good resolution but almost insensitive to g-flash)

  4. The micromesh technology • Micromesh is built by chemical treatments applied on coppered kapton • Support removed to increase the transparency

  5. The monitoring µMGAS used in 2010 • 10B4C (~0.7 µm) on a 1 µm coppered kapton(12.5 µm) • 5/25/5 µm (Cu/kapton/Cu) micromesh • ~18.5 mg 235UF4 (70 mm diam.) on 20 µm Al • 5/50/5 (Cu/kapton/Cu) micromesh • Entrance and exit windows: 12.5 µmkapton • Gas (~1 atm): Ar (88%) + CF4 (8%) + iCH4 (2%)

  6. Transmission from monitoring µMGAS(from Raul Sarmento)

  7. The XY-MGAS • Charges are collected through strips used to create an X–Y structure out of electrically connected pads • n_TOF XY µMGAS consists in: • 106x106 strips with a pitch of 550 µm • Strips are read by means of two 96 channels Gassiplex cards The effective center of the detector is not the geometrical one

  8. XY-signals

  9. Ongoing work with µMGAS • Fabrication of a new XY-MGAS since the current one shown some malfunctioning zones this year. • Mounting and electric connection of fission tagging µMGAS has to be improved. • Electronic needs to be improved: • signal is built by combining the energy output of a preamp and a TFA -> signal is too slow and the preamp is not suited for big signals or high count rate.

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