PID with AEROGEL, RICH and TOF

In addition to RICH, proposed AEROGEL, and EMCal-time-of-flight, additional TOF allows to enrich PID capabilities. The schematic diagram for PID with AEROGEL, RICH and TOF is shown in Fig. 14.

図 14: PID capabilities with AEROGEL, RICH and additional TOF. Aerogel is based on n = 1.010 with threshold at 10 % of maximum numner of photoelectrons. For the relation with Fig. 1, see text.

And the detail is described in the order from low to higher momentum for pion, kaon and (anti-)proton, separately in the following. The lower limit of the momentum is determined by the magnetic field (namely, lower than the limit, the partile is curled up by the magnetic field), and it is assumed here as 0.5 GeV/c.

As a whole, charged pion can be identified from 0.5 to 3.7 GeV/c and from 5.5 to 10 GeV/c (as high as momentum can be measured and statistics allows). Kaon and are identified from 0.5 to 3.7 GeV/c, and then 5.5 to 7.0 GeV/c. (Anti-)proton are identified from 0.5 to 4.2 GeV/c, and then 5.5 to 7.0 GeV/c. Those momentum range is based on (I) the TOF resolution is 100 ps, and (II)the AEROGEL threshold is at 10 % of the maximum number of photoelectrons.

One should need additional consideration when both AEROGEL and RICH counter are used for the veto counter for proton idnetification. If these are needed as a trigger, an additional trigger logic to identify as a charged track is required to reject photon. The charge track identification needs to be done, for example, by drift chamber, or pad chamber but cannot be done by EMCal that has response also for photon.

Note for the relation with Fig. 1

To reduce the gap between 3.7 GeV/c (for pion and kaon. For (anti-)proton it is 4.2 GeV/c.) and 5.5 GeV/c, it is needed either (i) RICH uses higher index of gas than 1 atm of $CO_2$ (n = 1.00041) in order to make the 5.5 GeV/c down, or (ii) separation with AEROGEL according to the pulse height (for momentum range more than 10 % of maximum number of photoelectron) is possible to make the 3.7 GeV/c up. And the region above 7.0 GeV/c (for kaon and proton), the method (ii) is needed.

Please note that in Fig. 1, the threshold is raised to some 50 % of maximum number of photoelectrons.

Pion identification

It is done first by TOF, from 0.5 GeV/c, up to 2.5 GeV/c. Then AEROGEL covers pion identification from 1 to 3.7 GeV/c (when kaon fires AEROGEL). There is operlap betweem 1 to 2.5 GeV/c, which allows to make cross check. Above 5.5 GeV/c, RICH takes care pion identification up to the highest momentum, where statistics and momentum measurement allows, and where it is less than 17 GeV/c (where kaon begins to contaminate into pion for RICH).

Kaon identification

Firtst, from 0.5 to 2.5 GeV/c, kaon identification is done by TOF as same way as pion. Second, from the 2.5 to 3.7 GeV/c, kaon PID is done veto-AEROGEL with TOF as non-(anti-)proton. Third, from 5.5 up to 7.0 GeV/c (when proton is contaminated into kaon), kaon PID is done by veto-RICH and AEROGEL.

Proton identification

First from 0.5 to 4.2 GeV/c, proton identification is done by TOF. Second, from 5.5 up to 7.0 GeV/c, proton is identified by veto-RICH and veto-AEROGEL with additional requirement as a charged track (but not as a photon).