We plan to have an engeneering run with the prototype Heavy Flavor Tracker. There will be (maybe not final version ) pixel detectors with 3 sectors (out of 10) + SSD + supports. The signal significance for the full HFT detector is obtained from the CDR simualtion results. The azimuthal acceptance is obtained from a fast MC calculation. This study is to show what geometry design of the 3 sectors is the best to achieve a reasonable physics goal in this engeneering run. Here are some assumptions:

• The absolute significance is obtained from the full HFT simulation, I didn't take into account the performance degration with missing IST and the non-final pixel detector.
• The fast MC only didn't consider the track bending in the magnetic field. For quick estimation, if the daughter phi is in the sector acceptance, I take it as accepted.
• particles are all at eta = 0.

I tried the following sector geometry design. Here "1" means the sector exists, while "0" does not. So "1110000000" will mean 3 adject sectors (certainly there is no special starting position in azimuthal as TPC is asimuthal symmetric). In the fast MC calculation, I tried the following 4 designs:

10010010000, 1110000000, 1100100000, 1100010000

Fig. 1 shows the average azimuthal acceptance while Fig. 2 shows the signal significance (S/sqrt(S+2B)) in 100M AuAu central (0-10%) events for different prototype designs.

Fig. 1 Azimuthal average acceptance of HFT prototype with different geometry designs

Fig. 2 Estimated significance (S/sqrt(S+2B)) in 100M AuAu central (0-10%) events for different prototype designs.

From Fig. 1 & 2, we can find the design "1001001000" has the maximum acceptance & significance in the D0 mean pt region (1-2 GeV/c). The conclusion is the same as what Howard Wieman got quite a while ago also with the fast MC calculation.

With only prototype and order of 100M central events, one can see the high pT measurement is marginal. So the main physics goal for the HFT prototype run will be to have a relative decent measurement on the charm spectrum (if possible in several centrality bins). Thus for the Run-12 BUR, for the HFT prototype physics, we can request 300M minibias and 300M central AuAu200 GeV events giving the Run10 experience.