X5 analysis: the problem! The muon spectrum is overwhelmed by the gamma radiation background. Tmax is not visible. Possibile solution to recover the muon spectrum in the bundle: 1) reconstruct a track in the BIS 2) Identify the tubes in the bundle hit by the track 3) Plot the spectrum Absorbtion factor 1

X5 setup BIS Bundle  The bundle first layer was disconnected ML1 ML2 We require at least 6 hits in the BIS to define a track Best algorithm: fully tracking in BIS + bundle. We are doing something simpler for lack of time.

BIS number of tracks Source off Entries: tracks: % 1 track: % 2 tracks: % >2 tracks - 2 % Entries: tracks: % 1 track: % 2 tracks: % >2 tracks - 5 % Absorbtion factor 1

Chamber occupancy Source off Mean: 5.0 RMS: 4.5 Mean: 5.1 RMS: 4.7 Mean: 2.9 RMS: 1.1

Chamber occupancy Mean: % RMS: 5.8 Mean: 26.5 – 22% RMS: 5.3 Mean: 7.4 – 43% RMS: 2.0 Abs 1

Chamber occupancy Mean: % RMS: 5.2 Mean: 19.0 – 16% RMS: 4.9 Mean: 5.7– 33% RMS: 1.8 Abs 1 (800 ns time window)

The algorithm - We divide the BIS tube in three regions according to the track radius - We built a doublet combination of the BIS first and second layer - Look-up table to get the bundle tubes associated to every combination It works for zero angle only! BIS tubes

Track categories Entries: (82% of events) 1-1 : 1-1: (76%) 1-3: 5000 (3%) 2-3: 4000 (3%) 1-1: track with hits in the first and second layer of BIS 1-3: track with hits in the first and third layer of BIS 2-3: track with hits in the second and third layer of BIS We use only tracks of categories 1-1 We loose about 25% of statistics Source off With abs 1 we have similar figures Event with one track

The “road”: two examples BIS tubes: Layer 2 Layer 3 Layer 4 Tube 3 Bundle tubes Tube 3 BIS tubes: Bundle tubes Tubes 3, 4 Tube 3 Tubes 3, 4

Source off: two examples Bundle: layer 2 – tube 1 Bundle: layer 3 – tube 4 No cut (calib) Selected hits No cut (calib) Selected hits No evident bias on T0 and Tmax. A depletion in the central part of the spectrum

Abs 1: two examples Bundle: layer 2 – tube 1 Bundle: layer 3 – tube 4 No cut selected No cut It appears a hint of tmax after the selection. The background is not completely gone. A bundle track fitting could help.