RITU and the GREAT Spectrometer

Transcription

1 RITU and the GREAT Spectrometer Cath Scholey Department of Physics University of Jyväskylä 19 th March rd TASCA Detector Group Meeting, GSI Darmstadt C. Scholey (JYFL, Finland) RITU and the GREAT Spectrometer 19/03/ / 19

2 The RITU nuclear landscape... I Sb Te Sn Z 50 Lr Md No Es Fm Bk Cf Am Cm Np Pu Pa U Ac Th Fr Ra At Rn Bi Po Tl Pb Au Hg Ir Pt Re Os Ta W Lu Hf Tm Yb Ho Er Dy N 126 First Observation of Excited States New Isotope Last Known Isotope (Karlsruher 1995) 82 C. Scholey (JYFL, Finland) RITU and the GREAT Spectrometer 19/03/ / 19

3 Detector Chamber D Q2 Q3 Q1 Target Chamber Helium Gas (~1mbar) RITU gas filled separator QDQQ, Original design C. Scholey (JYFL, Finland) RITU and the GREAT Spectrometer 19/03/ / 19

4 RITU gas filled separator QDQQ, New dipole chamber and Differential Pumping added in 2001 C. Scholey (JYFL, Finland) RITU and the GREAT Spectrometer 19/03/ / 19

5 Free path for ecoils and beam dump ar away at 90 o reduces ocal plane rate C. Scholey (JYFL, Finland) RITU and the GREAT Spectrometer 19/03/ / 19

6 3000 Effect of New Dipole Chamber 83 Kr MeV Beam Beam Gas window Q Target Q Target Beam Old System Beam recoils + beam New System DIFFERENTIAL PUMPING recoils + beam Dipole Recoils Beam Stop Dipole Recoils Scattered beam Recoils + = Scattered Beam = RECOILS very little scattered beam! Counts Counts Total Si Strip Detector Spectrum OLD CHAMBER NEW CHAMBER Beam Stop Energy in Si Detector C. Scholey (JYFL, Finland) RITU and the GREAT Spectrometer 19/03/ / 19

7 The GREAT Spectrometer -outside C. Scholey (JYFL, Finland) RITU and the GREAT Spectrometer 19/03/ / 19

8 The GREAT Spectrometer -inside C. Scholey (JYFL, Finland) RITU and the GREAT Spectrometer 19/03/ / 19

9 Multi Wire Proportional Counter, MWPC - TOF E Size mm, 2 Mylar windows to separate RITU He from the Isobutane and 1 to separate the isobutane from the focal plane vacuum chamber. The cathode is also Aluminised Mylar. The wires are 100µms copper C. Scholey (JYFL, Finland) RITU and the GREAT Spectrometer 19/03/ / 19

10 Gamma - Planar HPGe mm 150 mm thickness with 5mm strip pitch + Clover HPGe, 4 crystals each with 4-fold segmentation. Recoil- Multi-wire-proportional counter + 2 DSSD mm, 100,300,700 µm thickness 1mm strip pitch = 4800 pixels Electron - 28 PIN-diodes mm 500 µm thickness. Alpha and protons - 2 DSSD mm 100,300,700 µm thickness 1mm strip pitch = 4800 pixels Timing, TDR - Total Data Readout acquisition system. recoil MWPC PIN diode DSSSD Planar box Ge MWPC recoil DSSSD Planar Ge PIN diode box C. Scholey (JYFL, Finland) RITU and the GREAT Spectrometer 19/03/ / 19

11 The JUROGAM array + RITU + The GREAT spectrometer. τ Prompt γ s τ Isomer Delayed γ s τ g.s. τ α p Time Line: γ γ γ α(x,y,t) Events generated in GRAIN: R TOF ~500ns 2us TOF R(x,y,t,tof) DSSD OR us C. Scholey (JYFL, Finland) RITU and the GREAT Spectrometer 19/03/ / 19

12 With reset foil C. Scholey (JYFL, Finland) RITU and the GREAT Spectrometer 19/03/ / 19

13 With reset foil C. Scholey (JYFL, Finland) RITU and the GREAT Spectrometer 19/03/ / 19

14 Without reset foil C. Scholey (JYFL, Finland) RITU and the GREAT Spectrometer 19/03/ / 19

15 Without reset foil C. Scholey (JYFL, Finland) RITU and the GREAT Spectrometer 19/03/ / 19

16 Heavy Element, 250 Fm, RDT 48 Ca MeV 400ug/cm Target-like scattering 5000 Counts per channel Recoils 1000 Beam-like scattering Channel number C. Scholey (JYFL, Finland) RITU and the GREAT Spectrometer 19/03/ / 19

17 Heavy Element, 250 Fm, RDT C. Scholey (JYFL, Finland) RITU and the GREAT Spectrometer 19/03/ / 19

18 Heavy Element, 250 Fm, RDT C. Scholey (JYFL, Finland) RITU and the GREAT Spectrometer 19/03/ / 19

19 Double-sided Silicon Strip Detectors (DSSDs) alpha alpha correlation time 600ms recoil alpha correlation time 100ms C. Scholey (JYFL, Finland) RITU and the GREAT Spectrometer 19/03/ / 19

20 92 Mo( 78 Kr,p2n) 167 Ir σ=70µb 65 hours C. Scholey (JYFL, Finland) RITU and the GREAT Spectrometer 19/03/ / 19

21 106 Cd( 58 Ni,p4n) 159 Re σ=1nbarn 3 days 162 Os 159 Re p 158 W C. Scholey (JYFL, Finland) RITU and the GREAT Spectrometer 19/03/ / 19

22 96 Ru( 78 Kr,2pn) 171 Pt σ=80µb 7 days α X-ray β X-ray 90 (a) Delayed Gamma Rays COUNTS (b) Alphas (c) Prompt Gamma Rays ENERGY (kev) C. Scholey (JYFL, Finland) RITU and the GREAT Spectrometer 19/03/ / 19

23 To Summarize RITU upgrades of the millennium have greatly suppressed focal plane background. Reset foils are essential for symmetric reaction, but not necessary for heavy elements Monitoring rates and being able to distinguish recoils increases greatly the life expectancy of your Si detectors. Thanks for listening... C. Scholey (JYFL, Finland) RITU and the GREAT Spectrometer 19/03/ / 19