1 / 25

Test of PRISMA in Gas Filled Mode

Test of PRISMA in Gas Filled Mode. B.Guiot for PRISMA collaboration. INFN – Laboratori Nazionali di Legnaro. Motivation. Example: the hindrance phenomenon. Measurements of small fusion cross sections are experimentally challenging.

roscoe
Download Presentation

Test of PRISMA in Gas Filled Mode

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Test of PRISMA in Gas Filled Mode B.Guiot for PRISMA collaboration INFN – Laboratori Nazionali di Legnaro

  2. Motivation Example: the hindrance phenomenon Measurements of small fusion cross sections are experimentally challenging C.L. Jiang et al., Phys. Rev. Lett. 89 052701 (2002) : 60Ni+89Y C.L. Jiang et al., Phys. Rev. Lett. 93 012701 (2004) : 64Ni+64Ni

  3. Principles of operation of a gas-filled magnetic spectrometer gas vacuum to a first approximation, Br does not depend on v Charge states merge • Poor resolution (no single mass resolution) • Basically a high-efficiency separator • Typically operated at 0° for the detection of fusion evaporation residues

  4. The average charge state can be very low in gas for a slow, heavy ion • for a central trajectoryPrisma is limited to A<180 • By using non-central trajectory we can reach Br=1.5Tm Magnetic rigidity 252Fm Problems with magnetic rigidity 208Pb Prisma max. rigidity for central trajectory 176Hf 148Sm 112Sn 58Ni <q> according to Betz

  5. 1.5Tm Se Ni Ca projectile CN S Magnetic rigidity of Evaporation Residues Projectile and ER rigidity as a function of the target Z @ E=VB for all practical cases Forget reverse kinematics!

  6. EFB 3230 mm EFB 800 mm GFM operation of Prisma. General considerations Gas filling: 4He is the most popular but other gases should be tested detector C-foil window • Drift chamber not to be operated in gas: • mult.scattering with no focusing elements • cannot optimize gas pressure in magnets Gas filling Gate valve the drift-chamber + detectors can move back 70cm and more

  7. EFB EFB The setup for the GFM operation of Prisma 1.2Tm Prisma at 0° 1.5Tm detector shifted 30cm C-foil window 50mg/cm2 beam dump DRIFT Detector chamber

  8. new chamber for GFM det.

  9. Junction side Si strip detectors for the gas-filled mode operation Ohmic side 3 mm Matrix of 2 x 3 Si detectors Thickness ~ 300 mm Active area = 5 x 5 cm2, 16 resistive strips

  10. PA PA PA PA Electronics scheme X Pos. A Home made Electronics (PAs and shaping amplifiers) INFN NAPOLI ADC A A Discr Bit Pattern Discr Discr Y Pos. ADC 100W A Energy Trigger Delay = 100 ns CFD TDC Beam reference

  11. Summary and program PRISMA in GFM : adequate Bρ up to masses A~200  Focal plane detector : 6 Si strips detectors  10 × 15 cm2 Aim : fusion reactions studies ; no super heavy elements  Test of electronics Preliminary tests with Si and α-source : signals OK  Pre-amplifiers: crosstalk Under progress  Test of C-foil window with different gases Under progress Windows from GSI and LNL  In beam test : 58Ni (200 MeV) + 197Au , PRISMA @ 60° : end of june Test of spot size, transmission, beam separation vs energy and gas…

  12. 40Ca+172Dy 1Torr X • 65cm • 100cm • 150cm • 200cm Y 32S+184W 1Torr X Y ANAMARI Code • Section by section calculation using mid-section energy and <q> • via 1st order transfer matrix • Straggling added at the end of each section (assuming gaussian distribution ) • Charge exchange not taken into account (ok if mean free path is short) • Very fast being implemented one cannot optimize the pressure one cannot estimate the background Without charge exchange

  13. 1Torr He 216Th 48Ca ANAMARI Code 48Ca (200MeV) + 172Yb a216Th + 4n The program assumes a full charge state equilibration. As we will see, it may not be appropriate

  14. 65cm • 100cm • 150cm • 200cm 36S (160MeV) +184W a216Th + 4n X 48Ca (200MeV) +172Yb a216Th + 4n 1Torr 1Torr Y TRAJIG Code • 4th order Runge-Kutta trajectory calculations • Straggling added step by step, according to G.Amsel, G.Battistig, A.L’Hoir Nuc. Instr. Methods B201 (2003) 325 • Charge exchange included. Cross sections from A.S.Schlachter et al. Phys.Rev. A11 (1983) 3372 assuming detailed balance and 1e exchange approximation. • Yields reasonable results from high vacuum to large pressures above: first calculations without charge exchange

  15. TRAJIG Code Approximations used: • schematic (ideal) optical elements (no fringing field) • cross sections and charge distributions are calculated only once per section, • at the average estimated energy. The most critical approximations are related to the charge-exchange • The charge-exchange cross sections are estimated by • single electron loss or capture approximation plus ... • empirical adjustment in order to reproduce the assumed charge distribution cross sections: A.S.Schlachter et al. Phys.Rev. A11 (1983) 3372 charge distribution: R.O.Sayer, Revue Phys. Appl. 12, 1977, 1543.

  16. 10-5 mb 10-4 mb 10-2 mb 0.1 mb 0.2 mb 0.5 mb 1 mb 2 mb 5 mb 10 mb gas: Helium @60° 0° aperture Trajig calculation for 197Au 197Au

  17. Trajig calculation for @60° 0° aperture gas: Helium charge-exchange contribution multiple scattering contribution

  18. 197Au 58Ni Trajig calculation for @60° 0° aperture 0.01mb 0.1mb 0.5mb 1 mb 2 mb 3 mb 5 mb

  19. Trajig calculation for @60° 3° aperture 0.01mb 0.1mb 0.5mb 1 mb 2 mb 3 mb 58Ni 197Au 5 mb 58Ni 197Au

  20. Prisma @ 60° Calculated 2D XY spectrum 3° aperture Focal plane detector 2 mbar of He 197Au 58Ni

  21. Trajig calculation @60° gas: Argon 0° aperture 0.01mb 0.1mb 0.5mb 1 mb 2 mb 3 mb 5 mb 197Au 58Ni

  22. A fusion example 48Ca (200MeV) + 172Yb a216Ra + 2p2n 2mb He no charge exchange 48Ca 216Ra 172Yb with charge exchange

  23. other options 48Ca (200MeV) + 172Yb a216Ra + 2p2n 10mb He 48Ca ER 2mb Ar 48Ca ER

  24. How does GFM Prisma compare? • we cannot get into the SHE competition (accelerator and rigidity limitation) • we are ill equipped to compete in the HE spectroscopy (not with GFM) • a possibility is fusion reaction studies: it depends strongly on beam rejection, • necessary to measure at low cross sections and reliability of the simulations.

More Related