Status report Detector team Dirk Weißhaar IKP Köln

1. Status report Detector team Dirk Weißhaar IKP Köln • Acceptance test of three symmetric AGATA-detectors • - energy resolution with standard analogue electronics • - cross-talk with digital coincidence electronics (XIA) • In-beam test: position resolution for Doppler correction • - analysis is ongoing

5. Questions: • Fold dependent shift of add-back energies • Negative and positive outliers (>0.5keV) of • add-back energies

6. Core Cc Split charge Seg1 Seg2 Cseg1 Cseg2 Split charge model HV GΩ Core signal is AC-coupled to segments via bulk capacity CsegX ! Segment I sees Qind=Qcore*CsegI/(Cc+ΣCsegX)

7. Standard Cc of AGATA

8. For AGATA-detector bulk capacity of segments is ~1.3pF → 1.3pF/1246pF = 0.105% → shift 1.3MeV is ~1.4keV Notice: MINIBALL detector tested with Cc=5000pF should result in a shift of 0.15%. But measurement showed a shift of 0.54% (Cc=1200pf →0.59%).

9. Cf C21 pre1 Q1 Seg1 Seg2 Q2 pre2 Cross-talk, A. Pullia, Legnaro 2002 V1=Q1/Cf - Q2*C21/Cf2 Cf=1pF → C21=1fF yields to 0.1% crosstalk Eγ=E1+E2, a=C21/Cf, b=C12/Cf Emeasured=Eγ– aEγ- (b-a) E1 shift tilt Always Emeasured≤ Eγ

10. AGATA cold preamplifier 16mm

11. Crosstalk E1 → E2

12. Measurement of the tilt by unfolding 2-fold spectra in spectra Eγseg1> Eγseg2and Eγseg2 >Eγseg1

13. Position of cold preamps for nearest neighbours event

16. Conclusion for cross-talk • Split charge model solves • the fold dependent energy shift of the add-back spectra. • Preamplifier cross–talk yields a negative shift and a tilt • for the add-back energies. • No systematics has been found for the outliers in the add-back • spectra for the three detectors • (same cryostat, same cold and warm preamplifiers) • Model for positive outliers? • Nevertheless: cross-talk <10-3

18. ~ 15% of core peak intensity

21. The ‘bow’-effect only occurs in nearest neighbour add-back of front segments The ‘bow’-effect not occurs in any other 2-fold combination (also between not neighbouring front segments !)