ES Performance with Collisions

1. ES Performance with Collisions Dave Barney1, Anna Eliiott-Peisert1, Kai-Yi Kao3, Chia-Ming Kuo2, Syue-Wei Li2, Zong-Kai Liu2,Rong-Shyang Lu3, Yeng-Ming Tzeng31. CERN 2. National Central University 3. National Taiwan University 1

2. Occupancy Contact: Syue-Wei Li 2

3. The plots show the Preshower occupancy, defined as the percentage of strips with a signal at least 4xσnoise, as a function of η and Φ (averaged over all four planes) for 900 GeV, 2.36 TeV and 7 TeV Minimum Bias collision data. The Preshower was operated in High Gain mode during the data taking. Φ variations for the 900 GeV and 2.36 TeV data are due to the presence of a couple of hardware problems at specific positions, not present in the 7 TeV runs. At 7 TeV the Φ variations are due to the X-Y geometry of the Preshower and are well-modeled by simulation. The occupancy increases as a function of η and √s as expected. Contact: Syue-Wei Li 3

4. In-situ MIP calibration and comparison with pre-calibration Contact: Syue-Wei Li 4

5. The energy distribution for a silicon sensor (top), using charged tracks with momentum > 1 GeV/c pointing to the Preshower from 7 TeV Minimum Bias collision data. The Preshower was operated in High Gain mode during the data taking. The distributions are fitted by a Landau convoluted with a Gaussian function, represented by the blue line. The peak positions from distributions such as these define the “MIP” values for each sensor and are calculated for all sensors having >1000 RecHits (currently 3792/4288 sensors). In the example below the MIP is at 45.1 ADC counts. The bottom left plot shows the distribution of measured MIP values for the 3792 sensors having > 1000 RecHits. The bottom right plot shows the ratio of signal to noise for each sensor. Contact: Syue-Wei Li 5

6. (MIP from pre-calibration - MIP from collision) x 100 residual = MIP from pre-calibration The left plot shows the correlation between sensor MIP values obtained from 7 TeV Minimum Bias collision data and the pre-calibration made in the laboratory using cosmic rays. In both cases the Preshower was operated in high gain. The residual plot is shown on the right. The offset is due to the different particle momentum spectra in the two scenarios. The precision is around 3.8% w.r.t. the pre-calibration. Contact: Syue-Wei Li 6

7. TK-ES hit-matching efficiency Contact: Yeng-Ming Tzeng 7

8. Hit-matching efficiency (averaged over all four planes), defined as the probability of finding a hit in the Preshower within a window around extrapolations of charged tracks from the primary vertex, as a function of track pT for 7 TeV Minimum Bias collision data and simulation. The pT dependence is due to impurity of the track reconstruction algorithm. The plateau is not at 100% because of inefficiencies in the track associator tool; the same features are found in data and simulation. The hit-matching efficiency, presented in the last column of the table, is calculated by taking the ratio between data and simulation. 8

9. Energy deposit on ES planes Contact: Chia-Ming Kuo 9

10. The Preshower energy associated to endcap superclusters in the front (EES Clus 1(X)) and rear plane (EES Clus 2(Y)) and their ratio, with raw ET > 2 GeV. Data collected in Minimum Bias events at 2.36 (top) and 7 TeV (bottom) are compared to simulation. 10

11. ES-EE cluster position correlation Contact: Rong-Shyang Lu 11

12. The event displays shows the projected position (black point at (0,0)) of the seeded basic cluster of the EE super cluster on the X-Y plane and the associated ES clusters on the front plane (blue) and rear plane (red). One ES cluster, whose central position is indicated by E1, is found on the front plane and three ES clusters, whose central positions are indicated by E1, E2 and E3, are found on the rear plane. Note that the Preshower is finely segmented along X(Y)-direction on front(rear) planes. The combined ES position shown by the green dot is calculated using the most energetic ES sub-cluster in each plane. 12

13. The plots show the difference between the measured position by the seeded basic cluster of a given super cluster and most energetic ES cluster for 900 GeV and 7 TeV. Since the Preshower can only measure one direction well with one plane, it shows the better spatial resolution for X(Y)-direction on front(rear) plane. The residual between EE and ES strips perpendicular to the strip direction is dominated by the EE precision, to about 1 cm. The residual between EE and ES parallel to strip direction is dominated by ES strip length, to about 3 cm. Data are compared to MC. The mean shifts between data and MC are indicated in the bottom table. The results show the alignment between the ES and EE is good to the level of a couple of millimeters. Contact: Rong-Shyang Lu 13

14. Alignment w.r.t. tracker Contact: Kai-Yi Kao 14

15. Measured position residuals for each Preshower plane before (open circles) and after (solid circles) software alignment for 7 TeV Minimum Bias collision data. The width is dominated by the accuracy of the extrapolation of the tracks from the Tracker to the Preshower. 15

16. Supplement slides 16

17. Occupancy (Data vs. MC) 17

18. Strip fraction as a function of η for different Φ slices 18

19. ES-EE position residuals 19

20. Hit-matching efficiency as a function of η for 7 TeV Minimum Bias collision data and simulation for each of the four Preshower planes, averaged over all pT. Efficiency is defined as the probability of finding a hit in the Preshower within a window around extrapolations of charged tracks from the primary vertex. The ratio between data and simulation hit efficiency is also presented. The Preshower was operated in High Gain mode during the data taking. The η dependence and plateau value are due to inefficiencies of the track reconstruction algorithm and track associator tool respectively. 20

21. Hit matching efficiency as a function of Φ for 7 TeV Minimum Bias collision data and simulation for each of the four Preshower planes, averaged over all pT. Efficiency is defined as the probability of finding a hit in the Preshower within a window around extrapolations of charged tracks from the primary vertex. The ratio between data and simulation hit efficiency is also presented. The Preshower was operated in High Gain mode during the data taking. The Φ dependence and plateau value are due to inefficiencies of the track reconstruction algorithm and track associator tool respectively. 21