Position-Sensitive Si(Li) Transmission Detectors for the EXL-Experiments at GSI-Darmstadt D. Protić, T. Krings, S. Niessen, Forschungszentrum Jülich, Institut für Kernphysik (IKP), Jülich, Germany P. Egelhof, Gesellschaft für Schwerionenforschung (GSI), Darmstadt, Germany E. C. Pollacco, CEA Saclay, France ~ 6.5 mm thick the same structure as for the Si(Li) detectors for the MUST2-setup effective thickness below 5 m without position- sensitive structure design is identical to the MUST2- design all components have to be UHV- compatible T = 273 K EXL- 1 EXL-2 6.5 mm thick 6.4 mm thick p + -contact is structured Li-diffused contact has to be thinned • transmission type Si(Li) detector A large target-recoil detector will be constructed for the future EXL- experiments (EX otic nuclei studied in L ight-ion induced reactions) at the NESR storage ring of the future FAIR project at GSI-Darmstadt [1]. As a part of the recoil detector, position-sensitive Si(Li) transmission detectors (5 to 9 mm thick) are intended for construction of E-E charged- particle telescopes. Si(Li) detectors of transmission type has been an important aspect concerning the total-energy measurement for target recoils transversing the silicon E-E telescopes and stopped in inorganic scintillators placed behind the telescopes. Two ~7 mm thick Si(Li) transmission detectors equipped with 8 pads on the implanted p + -contact have being prepared for the test measurements at ESR (GSI-Darmstadt). To relieve the efforts for the first experiments a telescope configuration and position-sensitive structure very similar to that of the MUST2 experiment (SACLAY, ORSAY and GANIL) will be applied [2], but with UHV-capable components. Results of the test measurements in the laboratory are presented. Abstract References [1] www.gsi.de [2] E. C. Pollacco et al., to be published in Nucl. Instr. Meth. [3] D. Protić and T. Krings, “Development of transmission Si(Li) detectors”, IEEE Trans. Nucl. Sci., vol. 50, pp. 1008-1012, August 2003 MUST2-Si (Li ) setu p and modifications for the EXL- Si (Li ) setu p Si (Li ) detector protot ype for test measurements MACOR-blocks HV-board (ceramic) to replace ceramic boards MUST2-Si(Li) setup MUST2-Si(Li) setup PCBs out of FR4 Schematic view of the Si (Li ) transmission detector thinned Li-diffused n-contact covered with evaporated aluminum layer (effective thickness [3]: < 5 m) boron-implanted p + -contact covered with evaporated aluminum layer (thickness: < 1m) Al-bonded wires ~200 m wide connecting strips 8 position elements (pads) are separated by ~60 m wide and ~15 m deep plasma etched (SF 6 -plasma) grooves 3 to 5 mm wide guard- ring Li-compensated region (intrinsic zone) Conclusion and outlook • the manufacture of the two detectors will be completed within the next weeks. The Li-diffused contact of the Si(Li) detector EXL-1 will be thinned and the p + -contact of the Si(Li) detector EXL-2 will receive the position-sensitive structure. • UHV-capable components of the detector holder have been already finished • test measurements in UHV environment will be performed inside the ESR-ring at GSI-Darmstadt Si (Li ) detector EXL-1 in the UHV-com patible housin g p + -contact ceramic board Li-diffused contact (not yet thinned) (structured with 8 pads) (to contact the 8 pads) HV ceramic board MACOR blocks Specifications: Momentary status: • 8 pads on the boron-implanted contact • thin Li-diffused contact • operating bias: • energy resolution [FWHM] for 5.8 MeV -particles: • reverse current / pad: • resistance pad - neighbourhood: • housing / frame: 700 V < 50 keV < 250 nA > 1 M p + -contact is still without position- sentive structure ~ 3 m „thick“ Li- diffused contact see: Results of the first laboratory measurements the photolithography for performing the position-sensitive structure on the p + - contact is started up Results of the first laborator y measurements EXL- 1 EXL-2 operating bias: +700 V 298 K 283 K • energy resolution [FWHM] per pad for 5.8 MeV - particles 26-41 keV 25-30 keV 23-25 keV • reverse current per pad 110-200 nA 30-60 nA 15-31 nA • resistance pad - neighbourhood> 1 M > 1 M > 1 M • reverse current (total) 20 A 6.0 A 3.1 A 275 K • energy resolution [FWHM] per pad for pulser line 15-29 keV 13-20 keV 11-13 keV @ 273 K 1000 V 0.6 m 0.8 m 700 V 2.3 m 3.4 m 800 V 1.5 m 2.2 m 600 V 4.2 m 5.0 m @ 298 K effective thickness of the Li- diffused contact [3] determined with the help of - particles operating bias (n-contact) (p + -contact) to replace by UHV-capable parts VESPEL-blocks to replace to replace IEEE Nuclear Science Symposium, 29.10. – 4.11.2006, San Diego, USA Contact : [email protected], [email protected], [email protected] test measurements (energy resolution, reverse current, inter pad resistance) are being performed 54 mm 48 mm ~ 6.5 mm Ø 102 mm Ø 92 mm for the EXL collaboration