# FMS Days 166-173

For FMS data taken on day 166 -173

www.star.bnl.gov/protected/spin/heppelmann/run1017xxxx/MassPlots.html

Photons is included in the analysis if E_photon>5 (black) or E_photon>8(red)

for small cells and E_photon>2.5 (black) or E_photon> 3 for large cells.

Gains are taken as constant for all cells.

Mass Plots

This analysis includes events  from clusters of two and only two photons (described above) within an

angular radius of  0.035 Rad.

det=0 ->Large North

det=1->Large South

det=2->Small North

det=3->Small South

click on above links for plots in a multi page pdf file.

Each plot has a title that includes:

Mr[row#]_c[col#]_[det#]g([current gcorr] ->[suggested gcorr]) ([Energy of trigger peak], [Max Energy])

Plots are 9 per page with

page1:

row0-col0  .....      row0-col2

row1-col0 ......      row1-col2

row2-col0 ......      row2-col2

page2:

row3-col0 .....

etc.

Single Photon Energy Plots

A further set of multipage pdf's is shown for the single photon energy distributions for each cell.

Each reconstructed photons is associated with a particular cell after reconstruction.

Distributions are analyzed with fits from trigger peak energy to maximum energy with a red exponential fit over

that range.

A sub-trigger exponential fit is shown in black.

1) Again gains for all cells are constant.

2) A photon is included in this analysis if E_photon>5 (black) or E_photon>8(red)

for small cells and E_photon>2.5 (black) or E_photon> 3 for large cells.

So what if we Drop the large cell threshold from 30 GeV to 20 Gev

If we assume that the form for the energy dependence is exponential, over the relevant range around the trigger threshold:
Then we can calculate the change in trigger rate as a cell goes from a 30 GeV threshold to a 20 GeV threshold.
Using two actual Large Cells, the photon energy distributions for events pointing to a particular cell is below.

r25_c2_1 is a "hot" cell (Large South) r4_c8_1 is a "cold" cell (Large South) Fitted Expo Formula
Hot:  Number events per 1 GeV bin = Exp[10.36-.1156 E]
Integral above 30 GeV = 8500 events
Ingetral above 20 GeV = 27000 ~ 3.2 * 8500 events

Cold: Number events per1 GeV bin = Exp[7.343 - .1598 E]
Integral above 30 GeV = 78 events
Ingetral above 20 GeV = 388 ~ 4.9 * 78 events

Now imagine a channel like the cold one but with even lower gain and an expo slope of -0.28
Colder: Number events per1 GeV bin = Exp[7.343 - .28E]
Integral above 30 GeV ~ 1 events
Ingetral above 20 GeV = 20 events

Groups: