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-1EXL mm thick6.4 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 (EXotic nuclei studied in Light-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] [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 , August 2003 MUST2-Si(Li) setup and modifications for the EXL-Si(Li) setup Si(Li) detector prototype for test measurements MACOR-blocks HV-board (ceramic) to replace ceramic boards 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: < 1  m) 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-compatible housing 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 laboratory measurements EXL-1 EXL-2 operating bias: +700 V 298 K283 K energy resolution [FWHM] per pad for 5.8 MeV  -particles keV25-30 keV23-25 keV reverse current per pad nA30-60 nA15-31 nA resistance pad - neighbourhood > 1 M  reverse current (total) 20  A6.0  A3.1  A 275 K energy resolution [FWHM] per pad for pulser line keV13-20 keV K 1000 V 0.6  m0.8  m 700 V 2.3  m3.4  m 800 V 1.5  m2.2  m 600 V 4.2  m5.0  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 IEEE Nuclear Science Symposium, – , San Diego, USAContact: 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