Optical Tome Projection Chamber



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Principles of the OTPC operation

  The idea of detecting light instead of electric signals from a TPC was first considered in CERN and published
     in: Charpak, Dominik, Farbe, Gaudaen, Sauli, Suzuki, Nucl. Instr. Methods A 269 (1988) 142

  First publication on the Warsaw OTPC, illustrating the development phase:
     Ćwiok et al., IEEE TNS 52 (2005) 2895

  Description of the first prototype and test measurements in Dubna:
     Miernik et al., Nucl. Instr. Methods A 581 (2007) 194



Construction scheme
Principle of operation: an ion to be studied is stopped in the active volume, filled with a gas mixture and homogenous electric field; the ion and charged particles emitted in its decay ionize the gas; ionization electrons drift towards amplification section with a constant velocity; in the final stage of the charge amplification light is emitted which is recorded by means of a CCD camera and a photomultiplier tube (PMT); the signal from the PMT is sampled by a digital oscilloscope yielding the total light intensity as a function of time; combination of this information with the CCD image allows to reconstruct the particle's track in three dimensions; a special gating electrode is used to reduce the sensitivity of the chamber when the heavy ions are implanted; the first versions of the OTPC used wire-mesh electrodes in the amplification zone, later replaced by the GEM foils.


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