Pibero Djawotho

Indiana University

July 31, 2006

Simulation were done by Jason for the SVT review.

Figure 1: Fitted peak integral vs. fit residual sum (U+V) from st_jpsi input stream (J/psi trigger only). |
Figure 2: Fitted peak integral vs. fit residual sum (U+V) from st_physics input stream (all triggers except express stream triggers). |

The separation between photons and pions was achieved by using *Les cut* in the above figures where photons reside above the curve and pions below. The data set used is the st_jpsi express stream.

The transverse profile of an electromagnetic shower in the SMD can be parametrized by the equation below in each SMD plane:

f(x) is the energy in MeV as a function of SMD strip x. The algorithm performs a simultaneous fit in both the U and V plane. The maximal residual (data - fit) is then calculated. A single photon in the SMD should be well descibed by the equation above and therefore will have a smaller maximal residual. A neutral pion, which decays into two photons, should exhibit a larger maximal residual. Typically, the response would be a double peak, possibly a larger peak and a smaller peak corresponding to a softer photon.

This directory contains images of single event SMD responses in both U and V plane. The file name convention is SMD_RUN_EVENT.png. The fit function for a single peak is the one described in the section above with 5 parameters:

- p0 = yield (P
_{0}), area under the peak in MeV - p1 = mean (μ), center of peak in strips
- p2 = sigma of the first Gaussian (w
_{1}) - p3 = fraction of the amplitude of the second Gaussian with respect to the first one (B), fixed to 0.2
- p4 = ratio of the width of the second Gaussian to the width of the first one (w
_{2}/w_{1}), fixed to 3.5

- Proposal to Contstruct an Endcap Calorimeter for Spin Physics at STAR
- Appendix Simulation Studies of Direct Photon Production at STAR
- An Endcap Calorimeter for STAR Conceptual Design Report
- The STAR Endcap Electromagnetic Calorimeter (EEMC NIM)
- An Endcap Calorimeter for STAR Technical Design Update #1
- Jan's gamma/pi
^{0}algorithm - Endcap Calorimeter Proposal (HTML @ IUCF)
- STAR Note 401: An Endcap Electromagnetic Calorimeter for STAR--Conceptual Design Report
- Spin Effects at Suppercollider Energies