TRACKING TEAM Introduction What has been done What still needs to be done

Tracking Team started at the Global Level Processing meeting (15-16/05/2003 in Legnaro) Web site: Members: France: Strasbourg, Orsay Italy: Legnaro, Padova, Milano Poland: Krakow Roumania: Bucharest Sweden: Stockholm, Uppsala UK: York Team leader: A. Lopez-Martens

Aim of tracking - Read for each event the list of deposited energies and positions of all the interactions points in AGATA e 1, x 1, y 1,,z 1 e 2, x 2, y 2,z 2 ………………….. e n, x n, y n,z n - Disentangle the interaction points i.e reconstruct individual photon trajectories and write out photon energies, incident and scattering directions E 1, (  ) inc,1,(  ) sc,1 E 2, (  ) inc,2,(  ) sc,2 ……………………………… E i, (  ) inc,i,(  ) sc,i Doppler correction Polarization measurement Optimization:  ph x P/T

Physical Processes in Ge for photons Compton (10 keV) ~ 55  m (100 keV) ~ 0.3 cm (200 keV) ~ 1.1 cm (500 keV) ~ 2.3 cm (1 MeV) ~ 3.3 cm Photon range  (E) = M A /(N av.  ). 1/  E

1 2 3 source 11 22 e1e1 e2e2 e3e3 Property of Compton Scattering E0E0 cos(  i ) = 1 – m e c 2 (1/E  i – 1/E  i-1) ) incident energy at i scattered energy at i = E  i-1) -e i assuming that the e - is at rest, from conservation of energy & momentum: E1E1 E2E2 0

Electron momentum profile => change in scattering direction ! Some complications…… ! Interaction position  position of energy deposition e-e-  sc  inc  ! Interaction of neutrons or other particles => adds totally uncorrelated interaction points  ion /  Brem ~ E e- (MeV) /21.8 ! Rayleigh scattering => change in incident direction

Additional Complications … From PSA: uncertainty in position of interaction x x position resolution From preamp: energy threshold x x x x x From preprocessing: energy resolution x True interactions What comes out of PSA

Events of interest : total E absorption Series of Compton scatters + photoelectric interaction (which might be so close that PSA thinks it’s 1 single interaction point !) Single photoelectric interaction Pair production + Compton interactions + Photoelectric interactions

Existing Algorithms or Algorithms currently being developed -Clusterisation + forward tracking G. Schmid et al., NIM A 430 (1999) 69 D. Bazzacco, mgt* code A.Lopez-Martens et al., NIM A 533 (2004) 454 -Back-tracking algorithm J. Van der Marel and B. Cederwall, NIMA 437 (1999) 538 L. Milechina and B. Cederwall, NIMA 508 (2003) 394 A. Lopez-Martens et al., NIM A 533 (2004) Clusterisation + Probabilistic method I. Piqueras et al., NIMA 516 (2004) st hit identification with Fuzzy Logic and/or fuzzy cluster creation C. Rossi Alvarez D. Bucurescu (see corresponding talk)

What’s been decided/done Systematically use secondary particle tracking for simulations (default option in the Agata code) + 5mm packing distance Tracked gammas in the full 180/120/… configurations with all dead materials, capsules, cryostats,… and compared their performance ( Compared different algorithms with same simulated data ( A. Lopez- Martens et al., NIM A 533 (2004) 454) Started combining the good features of different algorithms Started tracking neutrons (see J. Ljungvall’s talk) Started checking background suppression capacities of algorithms (see E. Farnea’s talk)

Pair production event tracking (anything new ?) Single interaction points (anything better than what we have now ?) Improve background suppression of algorithms Take into account ancillary information (?) Use « real » position uncertainties within a detector Compute « real » effective distances in Ge (not assuming a 4  Ge shell)…….now done ? Produce data (what format ?) for data analysis Optimize tracking codes for speed Online implementation What needs to be done

Where is Waely ?