In order to achieve maximul position resolution also for delayed events, PA retiming for PDC tracking must be performed. Since PA relative offsets are known in the previous preliminal PA-PB analysis, now it can be activated. First of all, we do need channel-by-channel TDC calibration for DrT TDC used for PDC, and the result is tabulated here. A typical drift time distribution after PA re-timing (top) and dtdx conversion function evaluated from it (bottom) are shown below. Note that WE DO NEED INVERTING OPERATION FOR RAW TDC CHANNEL DISTRIBUTION , and then PA arrival timing can be subtracted. This is just due to common stop feature of DrT usage.
After the re-timing operation, residual distribution of the track reconstruction looks nice for K^+ also. The drastical improvement is shown in the comparison below. The real and dashed lines represent the y-residual distributions for PDC L arm after and before retiming operation, respectively. dt-dx conversion functions used are constructed by the total from run 69 to 90 for both. It is obvious that the operation works well, and give reliable tracking for delayed events also after that.
Since re-timing operation is successfully introduced, the long-term variation of PDC tracking resolution can be studied (and stabilized) all over the E549 production. The long-term variation of PDC tracking efficiency is shown below. Now, PA time detection is additionally required to PDC hit pattern to perform tracking, but we do not see any inefficiency compared to them without PA requirement (see, here ) for the comparison.
Run-by-run values for PDC tracking resolution is shown below. dt-dx functions are taken from that obtained with run 69-90. The resolution is much improved for K^+ run, but periodic? variation, which is exactly synchronizing to that obtained without PA retiming, Still remains. This can be removed by using neighboring runs to construct dt-dx.
We divide the production term, and apply relevant dt_dx function. The initial guess of the division is obtained as next table, and the resulting long-term variation is shown below.
| run number (init) | reference for dt-dx (init) | run number (1st) | reference for dt-dx (1st) | run number (2nd) | reference for dt-dx (2nd) |
|---|---|---|---|---|---|
| 69 - 83 | 69 - 83 | 69 - 83 | 69 - 83 | 69 - 83 | 69 - 83 |
| 84 - 92 | 84 - 90 | 84 - 92 | 84 - 90 | 84 - 92 | 69 - 90 |
| 93 - 104 | 93 - 102 | 93 - 104 | 93 - 102 | 93 - 104 | 93 - 102 |
| 105 - 115 | 105 - 111 | 105 - 109 | 105 - 109 | 105 - 106 | 105 - 111 |
| 116 - 135 | 116 - 124 | 110 | 105 - 111 | 107 - 109 | 105 - 109 |
| 136 - 141 | 136 - 141 | 111 - 115 | 111 - 115 | 110 - 112 | 105 - 111 |
| 142 - 167 | 69 - 90 | 116 - 119 | 116 - 124 | 113 - 115 | 111 - 115 |
| 168 - 175 | 168 - 174 | 120 - 123 | 120 - 123 | 116 - 135 | 69 - 90 |
| 176 - 195 | 176 - 185 | 124 - 135 | 116 - 124 | 136 - 141 | 136 - 141 |
| 196 - 204 | 196 - 204 | 136 - 141 | 136 - 141 | 142 - 166 | 69 - 90 |
| 205 - 227 | 209 - 220 | 142 - 166 | 69 - 90 | 167 - 172 | 167 - 172 |
| 228 - 238 | 228 - 233 | 167 - 172 | 167 - 172 | 173 - 175 | 168 - 174 |
| 239 - 257 | 239 - 256 | 173 - 175 | 168 - 174 | 176 - 178 | 176 - 185 |
| 258 - 265 | 258 - 265 | 176 - 178 | 176 - 185 | 179 - 182 | 179 - 182 |
| 266 - 281 | 266 - 278 | 179 - 182 | 179 - 182 | 183 - 195 | 176 - 185 |
| 282 - 289 | 282 - 289 | 183 - 195 | 176 - 185 | 196 - 197 | 196 - 204 |
| 290 - 297 | 290 - 297 | 196 - 197 | 196 - 204 | 198 - 203 | 198 - 203 |
| 298 - 306 | 298 - 306 | 198 - 203 | 198 - 203 | 204 | 196 - 204 |
| 204 | 196 - 204 | 205 - 220 | 209 - 220 | ||
| 205 - 220 | 209 - 220 | 221 - 227 | 221 - 227 | ||
| 221 - 227 | 221 - 227 | 228 - 230 | 228 - 233 | ||
| 228 - 230 | 228 - 233 | 231 - 233 | 231 - 233 | ||
| 231 - 233 | 231 - 233 | 234 - 238 | 228 - 233 | ||
| 234 - 238 | 228 - 233 | 239 - 248 | 239 - 256 | ||
| 239 - 248 | 239 - 256 | 249 - 254 | 249 - 254 | ||
| 249 - 254 | 249 - 254 | 255 - 257 | 239 - 256 | ||
| 255 - 257 | 239 - 256 | 258 - 259 | 258 - 265 | ||
| 258 - 259 | 258 - 265 | 260 - 265 | 260 - 265 | ||
| 260 - 265 | 260 - 265 | 266 - 268 | 266 - 278 | ||
| 266 - 268 | 266 - 278 | 269 - 275 | 269 - 275 | ||
| 269 - 275 | 269 - 275 | 276 - 281 | 266 - 278 | ||
| 276 - 281 | 266 - 278 | 282 - 289 | 282 - 289 | ||
| 282 - 289 | 282 - 289 | 290 - 297 | 290 - 297 | ||
| 290 - 297 | 290 - 297 | 298 - 306 | 298 - 306 | ||
| 298 - 306 | 298 - 306 |
As the result of initial division, the long-term variation is supressed, but still exist. We apply further division of the production term and the further division is shown in the table abobe. The step-wise improvement is shown below. Now, PDC tracking has been finalized.
To be done nextly (in order) ....
0. PA->PB TOF finalization for K^+ runs.
1. NC analysis 1 - Detector study, energy calibration and correlation between PB-defined-1/beta and PB+NT-defined-total energy.
2. T0->PA TOF, Kaon flight time and relative offset adjustment of T0 segments.
3. Stop K selection with reaction time and inclusive proton spectrum
4. NC analysis 2 - PA->NC TOF with K^+ run
5. NC analysis 3 - Pattern recognition and 1/beta spectrum for neutral particles