Progress report NeuLAND

1. Progress report NeuLAND Collaboration meeting in Göteborg, Sweden, October 13-16, 2008 T. Aumann, K. Boretzky, H. Emling, J. Hehner, M. Heil, K. Mahata, Y. Leifels, W. Prokopowicz, R. Reifarth, D. Rossi, G. Schrieder, M. Elvers (Uni Köln) Outline Short reminder about NeuLAND Timing RPC concept Open questions - Impedance matching RPC prototype at GSI Next steps

2. NeuLAND detection of relativistic neutrons in a ToF spectrometer reconstruction of projectile excitation energy exclusive measurements aiming for up to DE=30 keV at 1 MeV NeuLAND introduction RPC concept Open questions RPC prototype Impedance matching Outlook Reactions with Relativistic Radioactive Beams

3. NeuLAND design goals • Time Resolution < 100 ps • Position Resolution ~ 1 cm • Excitation Energy Resolution~ 100 keV • x,y – Same Size as LAND2 m x 2 m • z – Length< 1 m • Neutron Efficiency> 90% for 1-n hits • Improvement of multi-n recognition NeuLAND introduction RPC concept Open questions RPC prototype Impedance matching Outlook Timing RPC (Resistive Plate Chamber) concept GSIHADES FOPI CERNHARP ALICE minimum ionizing particles

4. RPC principle p n Fe (ln≈ 17 cm) Kapton Float Glass (~ 1012W/cm, ln≈ 12 cm) Spacer (Fishing Line) GAS 85% C2H2F4 + 10% SF6 + 5% iso – C4H10 NeuLAND introduction RPC concept Open questions RPC prototype Impedance matching Outlook Detect protons from hadronic showers in converter (Fe)

5. Geometry of NeuLAND NeuLAND introduction RPC concept Open questions RPC prototype Impedance matching Outlook 200 cm 4×50 cm • total 140 m2 RPC • approx. 104 channels • each module hanging on slide rod • total weight app. 15 t

6. Questions to be answered by tests with prototypes • Number of gaps • Material for high voltage layers • Impedance matching by - adjusting the geometry (width of anode stripes, ...) - impedance matching with electronics • Cross talk (distance between stripes) • Differential or single ended readout • Handling of material (e.g. large glass plates ...) • Mechanical stability • ... Prototypes from FZ Dresden-Rossendorf and GSI NeuLAND introduction RPC concept Open questions RPC prototype Impedance matching Outlook

7. GSI prototype • active area: • 400 x 200 mm² • number of gaps: • 8 (variable) • thickness of glass plates: • 0.5 mm • gap size: 300 µm, distance holder: fishing lines • anode from 4 mm thick iron plate, strip width: 25 mm • outer electrodes: 2mm thick iron plates • electrode material: graphite spray (OKS 511) NeuLAND introduction RPC concept Open questions RPC prototype Impedance matching Outlook

8. Pictures Anode structure Isolation with Kapton NeuLAND introduction RPC concept Open questions RPC prototype Impedance matching Outlook Full assembly HV electrode (carbon layer)

9. Problem: Impedance matching • Small signals are expected. • Measured impedance is 9.5 W⇔ preamp 50 W. • Impedance matching will improve signal amplitude and shape. • Measurements with network analyzer show large reflections. NeuLAND introduction RPC concept Open questions RPC prototype Impedance matching Outlook reflection [dB] 50% transmission [dB] 10% frequency [GHz]

10. Impedance matching with transformers 10% reflection [dB] 1% frequency [GHz] NeuLAND introduction RPC concept Open questions RPC prototype Impedance matching Outlook 10Ω preamp anode strip 50Ω 1.5pF 8.2pF Good transmission for wide frequency band!

11. Impedance matching with transformers NeuLAND introduction RPC concept Open questions RPC prototype Impedance matching Outlook Transformers

12. Results of impedance matching with transformers reflection [dB] transmission [dB] frequency [GHz] Transmission improved but not for all frequencies! NeuLAND introduction RPC concept Open questions RPC prototype Impedance matching Outlook 50% 10%

13. Next steps • Continue network analyzer tests • Application of gas and HV • Measurement with source / cosmics • Determination of cross talk etc. • Investigate readout possibilities • single ended FOPI preamp cards • differential read out (PADI?) • HADES like single ended read out • other developments? • Test with electron beam NeuLAND introduction RPC concept Open questions RPC prototype Impedance matching Outlook

15. Impedance matching Measured impedance is 9.5 W. This will cause problems in connection with usual 50 preamplifiers. About 9.5 Ohm Impedance inside RPC Pin Begin RPC End RPC Cable

16. NeuLAND working group FZ Dresden-Rossendorf: D. Bemmerer, A. Wagner, D. Yakorev GSI, Darmstadt: T. Aumann, K. Boretzky, H. Emling, M. Heil, K. Mahata, Y. Leifels, W. Prokopowicz, R. Reifarth, G. Schrieder, ISS, Bucharest: M. Haiduc, C.M. Ilie, M. Potlog Jagellonski University, Krakow: R. Kulessa Johann Wolfgang Goethe Universität, Frankfurt: J. Stroth Johannes Gutenberg-Universität, Mainz: J.V. Kratz, D. Rossi KVI, Groningen:Catherine Rigollet SINP, Kolkata: S. Bhattacharya, U. Datta Pramanik University Cologne: M. Elvers, A. Zilges University of Santiago de Compostela: H. Alvarez-Pol, J. Benlliure, E. Casarejos

17. Pictures NeuLAND introduction RPC concept RPC prototype Open questions Impedance matching Outlook Anode structure

18. Pictures Isolation with Kapton NeuLAND introduction RPC concept RPC prototype Open questions Impedance matching Outlook

19. Pictures NeuLAND introduction RPC concept RPC prototype Open questions Impedance matching Outlook HV electrode (carbon layer)

20. Pictures NeuLAND introduction RPC concept RPC prototype Open questions Impedance matching Outlook Full assembly