Support to the event location in CS Scanning Station Fabio Pupilli LNGS Scanning Team OPERA Collaboration Meeting 02/04/2009 ANKARA

Analysis types in CS Scanning Station 1.Two basetrack search (STANDARD) 2.In case the event is not located: (MICRO) –Compton alignment –¾ search 3.Support to labs when the event is not localized in ECC (ON_REQUEST) –Doublet ReMapping and ¾ search after Compton alignment –Check of scan forth tracks or tracks found in brick to validate events This talk’s subject Updated to 24/03/2009

LAB REQUEST - Detailed analysis procedure Events not located with CS predictions 1.¾ search a.Event display with CS candidates superimposed to TT hits b.Search for rock-μ, cosmic tracks, tracks belonging to other events with Artem tool for CS candidate validation c.Compton Map Alignment The software (developed by Valeri and recently updated) compute the x-y offsets between the 2 CSd sheets in order to maximise the number of Compton electron track coincidence. The alignment is performed locally, sampling the scanned area with small zones The size of the zones is established by the minimum number of tracks of the alignment peak; tuning this parameter we can increase the signal/noise and obtain “good” maps for CSD of (more or less) any Fog level (previously we could select only “a priori” the area-size) – Good Map – One zone corrected The offset of the “wrong” zone is corrected a posteriori averaging the nearest zone offsets

Compton Map - Upgrade

Events not located with CS predictions 1.¾ search a.Event display with CS candidates superimposed to TT hits b.Search for rock-μ, cosmic tracks, tracks belonging to other events with Artem tool for CS candidate validation c.Compton Map Alignment d.New link between CS1 and CS2 LAB REQUEST - Detailed analysis procedure PositionTolerance = 8 μm (both for double base-tracks and 3 out of 4) [in STANDARD analysis 40 μm] SlopeTolerance = 10 mrad (double base-track ) SlopeTolerance = 50 mrad (3 out of 4) MinGrainSum = 36 (double base-track ) MinGrainSum = 30 (3 out of 4) σ ~ 1.1 μm

Events not located with CS predictions 1.¾ search a.Event display with CS candidates superimposed to TT hits b.Search for rock-μ, cosmic tracks, tracks belonging to other events with Artem tool for CS candidate validation c.Compton Map Alignment d.New link between CS1 and CS2 e.Discard or “confirm” already validated candidates f.Manual check LAB REQUEST - Detailed analysis procedure All new double bt are checked; a selection is applied on ¾ sample depending on the event: -QE events: only μ candidates checked (bt slope within 100 mrad wrt EleDet pred) -Other events: cuts applied in order to reduce the number of tracks to be checked to 20÷30 (for CC all μ candidates are always checked): I.Cut on number of grains II.Stronger Quality-Cut on the basetrack: “σ < 0.25*N -4”

Events not located with CS predictions 1.¾ search a.Event display with CS candidates superimposed to TT hits b.Search for rock-μ, cosmic tracks, tracks belonging to other events with Artem tool for CS candidate validation c.Compton Map Alignment d.New link between CS1 and CS2 e.Discard or “confirm” already validated candidates f.Manual check g.Analysis of the results LAB REQUEST - Detailed analysis procedure Check if new candidates are tagged as comsic rays, rock-μ or track belonging to other events; TT matching of new candidates

LAB REQUEST - Detailed analysis procedure Events not located with CS predictions 1.¾ search a.Event display with CS candidates superimposed to TT hits b.Search for rock-μ, cosmic tracks, tracks belonging to other events with Artem tool for CS candidate validation c.Compton Map Alignment d.New link between CS1 and CS2 e.Discard or “confirm” already validated candidates f.Manual check g.Analysis of the results 2. If no new (interesting) tracks found – ReScan a.Manual check of new candidates b.If nothing new found, we repeat steps c,d,e,f,g of the previous analysis. We evaluate also measurement’s Data Quality and if it’s not satisfactory we can sometimes schedule another scan

LAB REQUEST - Detailed analysis procedure Events not located with CS predictions 1.¾ search a.“Eye” check of the event and electronic detector prediction with CS candidates superimposed b.Search vetoed CS tracks (rock-μ, cosmic tracks, tracks belonging to other events) with Artem tool c.Compton Map Alignment d.New link between CS1 and CS2 e.Discard or “confirm” already validated candidates f.Manual check g.Analysis of the results 2. If no new (interesting) tracks found – ReScan a.Manual check of new candidates b.If nothing new found, we repeat steps c,d,e,f,g of the previous analysis. We evaluate also measurement’s Data Quality and if it’s not satisfactory we can sometimes schedule another scan Validation of tracks originated in the brick –Manual check of tracks found in the brick for event validation –(If not found) Search for single basetracks in the data and manual check –To be implemented: Prediction scan on CSD (3x3 views) around these tracks

LAB requests arrived 56 support requests from European Labs arrived at LNGS None of the CS tracks connected in brick: 16 At least one CS track connected, but event not localized: 29 Check on Scan Forth (SF) tracks to validate the event: 8 CS candidates “confirmation” with Compton Map: 3 Results Still under analysis: 26 Completed: 30 I.Second brick extraction request: 4 II.No new tracks / no SF tracks confirmed: 1/1 III.Compton Map Confirmation: 3 IV.New tracks published or SF track confirmed: 21 Feedback by LABS 9 events localized, 5 CSD with SF tracks confirmed 4 event with new tracks connected

Completed – 2° brick extraction Event (NC) - Brick STANDARD analysis: 2 CS candidates not connected in the brick

Completed – 2° brick extraction Event (NC) - Brick ON_REQUEST analysis: 1. ComptonMap confirms only one of the candidates previously validated ( but marginal in X, projection on ~ 800 μm from the edge ) 2.No new tracks found Requested extraction of adjacent brick in X (124810)

Completed – Event located Event (CC) - Brick STANDARD analysis: 3 CS candidates not connected in the brick

ON_REQUEST analysis: 1. ComptonMap discards one candidate (ID = 1) and confirms other candidates 2.A mu candidate (ID 3) recovered in ¾ sample Completed – Event located Event (CC) - Brick Event located, track 3 is the muon

Completed after a two step analysis – Event located Event (CC) - Brick STANDARD analysis: 2 CS candidates connected in the brick, but uncorrelated

Completed after a two step analysis – Event located Event (CC) - Brick ON_REQUEST analysis: 1. ComptonMap confirms all candidates previously validated 2.Found 5 new candidates in ¾ sample New candidates connected, but not sufficient to reach primary vertex 1° Step

Completed after a two step analysis – Event located Event (CC) - Brick ON_REQUEST analysis (ReScan): Found a new track (ID1,green) New candidate connected, event located 2° Step

Completed – Event located Event (CC) - Brick STANDARD analysis: No double bt found in CSd MICRO analysis: one CS candidate found but not connected in the brick

Completed – Event located Event (CC) - Brick Since the only track validated on CS came from a ¾ analysis, the first step of ON_REQUEST analysis was a ReScan and… Surprise! Found 6 confirmed double bt (including a mu candidate, ID 2) from ReScan

Completed – Event located Event (CC) - Brick It’s difficult to explain a null result on first scanning, when the second scanning has measured 6 double bt (5 in the previously scanned area), only by scanning inefficiency. But take a look at first scanning’s Compton Map: Large offsets, in most zones more than 40 μm Marks measurement error? Why after Compton alignment we cannot recover tracks?

Completed – Event located Event (CC) - Brick We tried to search in scanning data of the first scanning for single basetracks or double basetracks (enalrging position tolerance), compatible with tracks found on second scanning The explanation… Tracks 2,7,8 found as single bt Tracks 5,6 found as double bt but with large offsets (not linked after Compton alignment because they are at the border between two zones with different offsets)

Completed – Event located Event (CC) - Brick All tracks have been connected in the brick Event located, track 2 is the muon

CS candidate tagged – Under Analysis Event (CC) - Brick STANDARD analysis: 1 CS candidate not connected in the brick

CS candidate tagged – Under Analysis Event (CC) - Brick Using Artem tool, we realized that this track is a rock-μ

Compton Map “confirmation” Event (CC) - Brick Mu candidate and 2 other candidates found in STANDARD analysis but not connected Tracks are not tagged by Artem tool ComptonMap confirms all candidates Checked also 5th mark to confirm CS- brick correlation

Conclusions Support activity to Lab requests in LNGS Scanning Station is on going with good results The activities have been slowed down in the last two months to concentrate efforts in localizing pending events The time dedicated to each request is affected by the heavy load of manual checks required especially for ¾ analysis, which should be reduced with some dedicated software Hope to send other good news to European Labs in next weeks…