Study of 58 Ni excited states by (p, p’) inelastic scattering

1. Study of 58Ni excited states by (p, p’) inelastic scattering A primer course of experimental nuclear and particle physics Osaka University, 2009

2. Outline • Introduction • Experiment • RAIDEN spectrometer • Detectors, electronics & DAQ • Online tuning • Data analysis • State identification • Differential cross section • BG treatment • Result • Summary • Acknowledgements the Spectrometer Group

3. Introduction: inelastic scattering • Inelastic scattering: (in a non-relativistic view) at a given angle … excitation states are measurable elastic term excitation term observable * the Spectrometer Group

4. Introduction: spectrometer • Spectrometer = prism • Distinguishes particles with different momentum • Well designed magnets are required to guarantee precise measurement g-1<<1 in a small range the Spectrometer Group

5. Introduction: DWBA • Distorted wave Born approximation • 2-step scattering • Cross section • “DW”: elastic solution for as the zero order of final wave function • “BA”: only the first order correction from is considered • Refer to “Introduction to nuclear reactions”, G.R. Stachler, 1980 elastic term inelastic perturbation the Spectrometer Group

6. Experiment: overview • RAIDEN @ RCNP • Proton beam at 53 MeV energy from AVF • DW = 2.7 msr (slit), SWPC, plastic DE-E counters • (CH2)m, 58Ni[0.92 mg/cm2] and nat.Mg[0.58 mg/cm2] • ~ 20 hour beam time • CAMAC + Tamii DAQ + PAW • N.T. Huong, D.N. Thang, P.W. Zhao, Y. Lei, Y. Wang, and W. Guo the Spectrometer Group

7. Experiment: RAIDEN @ RCNP • RAIDEN spectrometer: NIM 175 (1980) 335 Incredible: 30 years old but still works well! the Spectrometer Group

8. Experiment: detectors Single Wire Proportional ChamberNIM 196(1982)249; NIM 217(1983)441 Side view • Signals: • QL, QR position • DE1, DE2 • DEL, DER, Time • EL, ER, Time • RF Time “Charge Division” Ar+CO2 5% the Spectrometer Group

9. V x Experiment: detectors Plastic Scintillater the Spectrometer Group

10. Experiment: targets the Spectrometer Group

11. Experiment: electronics Fast signals Slow signals Busy-resistant logic the Spectrometer Group Coincidence logic

12. Experiment: online tuning • Electronics: • Gain of amplifiers: match the pulse heights • CFD tuning: suppress major part of noise • Delay tuning: establish coincidence / trigger logic • Gate width tuning: match rising time of Int. Amp. • Beam: • Identify the elastic peak • Adjust magnetic field to exclude the elastic peak • Rotate RAIDEN (from 15o to 50o ) during measurement the Spectrometer Group

13. Experiment: identification of state • In our experiment, the outgoing particles (p) move in magnetic field of spectrometer like in fig: Bρ = pout /q pout ↑→ ρ ↑ & Eout+ Ex +Krecoil = Ein(const) pout↑→↓Ex(small region~linear) the Spectrometer Group

14. On the other hand: ρcorresponding with x →Ex ~x From data analysis we get the position spectrum of proton (θ=150) the Spectrometer Group

15. 2+(1454) 3-(4475) 2+(3265) 2+(3038) 4+(4755) 4+(2460) 4+(3621) • By using online analysis, we can identify g.s and 1st excited state. Using table 1 refer [1] we can determine L=2+ , parity and Ex =1.454Mev of 1st the Spectrometer Group

16. And also, the L=3- (4475kev) state can be identify by using this table: • For other states We can identify by using the assumption Ex~x (linear) the Spectrometer Group

17. In face, the proportion between Ex and x is second-order linear like in fig • Therefore, by using this simple way, we can identify for other scattering angles. the Spectrometer Group

18. Data analysis: run summary Summary table the Spectrometer Group

19. Data analysis: cross section calculation • , C: the count of the state, Q: the total charge of incoming beam, r the reduced density of target, e the charge of proton, k the detecting efficiency, and DW the solid angle the Spectrometer Group

20. Data analysis: background treatment • ADC overflow of measured charge: which cause a pile- up at x = L/2 the Spectrometer Group

21. Data analysis: background treatment • QL, QR drifts caused by pre-amp resistance / ADC zero level: result in error on x calculation the Spectrometer Group

22. Data analysis: background treatment 300 • Drift of PMTs of plastic E counter: signal & BG not orthogonal 205 here the Spectrometer Group

23. Data analysis: background treatment • Drift of PMTs of plastic E counter: signal & BG orthogonal now the Spectrometer Group

24. Data analysis: background treatment the Spectrometer Group

25. Data analysis: ds/dW & DWBA cal. Fresco: http://www.fresco.org.uk/ After BG reduction Statistic error only. the Spectrometer Group

26. We have learned • The excitation states of 58Ni have been measured by inelastic proton scattering at Ep = 53 MeV; • The excitation energy and angular momentum of these excitation state have been determined; • The angular distributions of differential scattering cross section, which are well agreed with the DWBA calculations, have been obtained from the experimental data. the Spectrometer Group

27. Summary • Nuclear reaction theory with Born approximation • Determination of the angular momentum of excited states • Prepare of the target. • Detection of charged particles with a single-wire proportional chamber and plastic scintillators and their operation. • Electric circuits and a CAMAC based data acquistion system • Data analysis, determination of differential cross section the Spectrometer Group

28. Acknowledgements • Osaka University, JSPS, JICA, • Department of physics, RCNP, AVF operators • Organizers: Prof. T. KISHIMOTO, Prof. M. NOMACHI, • Prof. Y. KUNO, Prof. T. OGAWA, etal. • Lectures: Prof. T. NAKANO, Prof. T.YAMANAKA, • Prof. M. FUKUDA, etal. • Experiment: Prof. Y. FUJITA, Prof. A.TAMII, Prof. H. OKAMURA, • Prof. K. HIROTA, Prof. T. ITAHASHI, etal. • All the secretaries, • All the participants of this prime school the Spectrometer Group

29. the Spectrometer Group

30. the Spectrometer Group

31. the Spectrometer Group

32. the Spectrometer Group

33. Thank you A primer course of experimental nuclear and particle physics Osaka University, 2009

34. Appendix: elastic term the Spectrometer Group

35. Appendix: detector arrangement the Spectrometer Group

36. Trigger Appendix: timing chart DAQ system GDG FIFO VETO CCNET BUSY CCNET BUSY GDG the Spectrometer Group

37. Appendix: excited states of 58Ni the Spectrometer Group

38. Appendix: ds/dW & DWBA calculation the Spectrometer Group

39. Appendix: ds/dW & DWBA calculation the Spectrometer Group

40. Appendix: ds/dW & DWBA calculation the Spectrometer Group

41. Appendix: ds/dW & DWBA calculation the Spectrometer Group

42. Appendix: ds/dW & DWBA calculation the Spectrometer Group