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Study of 58Ni excited states by (p, p’) inelastic scattering
A primer course of experimental nuclear and particle physics Osaka University, 2009
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Outline Introduction Experiment Data analysis Summary Acknowledgements
RAIDEN spectrometer Detectors, electronics & DAQ Online tuning Data analysis State identification Differential cross section BG treatment Result Summary Acknowledgements Mar. 19, 2009 the Spectrometer Group
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Introduction: inelastic scattering
Inelastic scattering: (in a non-relativistic view) at a given angle … excitation states are measurable observable elastic term excitation term * Mar. 19, 2009 the Spectrometer Group
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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 Mar. 19, 2009 the Spectrometer Group
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inelastic perturbation
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 Mar. 19, 2009 the Spectrometer Group
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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 Mar. 19, 2009 the Spectrometer Group
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Experiment: RAIDEN @ RCNP
RAIDEN spectrometer: NIM 175 (1980) 335 Incredible: 30 years old but still works well! Mar. 19, 2009 the Spectrometer Group
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Experiment: detectors
Single Wire Proportional Chamber NIM 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% Mar. 19, 2009 the Spectrometer Group
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Experiment: detectors
V Plastic Scintillater Mar. 19, 2009 the Spectrometer Group
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Experiment: targets Mar. 19, 2009 the Spectrometer Group
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Experiment: electronics
Fast signals Slow signals Busy-resistant logic Mar. 19, 2009 Coincidence logic the Spectrometer Group
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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 Mar. 19, 2009 the Spectrometer Group
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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) Mar. 19, 2009 the Spectrometer Group
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On the other hand: ρcorresponding with x →Ex ~x From data analysis
we get the position spectrum of proton (θ=150) Mar. 19, 2009 the Spectrometer Group
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By using online analysis, we can identify g.s and 1st excited state.
2+(1454) 4+(2460) 2+(3038) 2+(3265) 4+(3621) 3-(4475) 4+(4755) 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 Mar. 19, 2009 the Spectrometer Group
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by using the assumption Ex~x (linear)
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) Mar. 19, 2009 the Spectrometer Group
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identify for other scattering angles.
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. Mar. 19, 2009 the Spectrometer Group
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Data analysis: run summary
B [mT] Brho [Tm] q [deg] Tar I [nA] Trig Live Q [nC] LAB C.M. 001 1.0674 15 15.2 58Ni 20 Tuning runs 002 1.0359 003 1.0469 2.25 004 697.93 30 177270 171667 005 20.2 45 79053 76555 007 43 44468 43204 008 25 25.3 35 88817 86947 010 30.4 48-65 145175 141972 011 35.5 68 130913 129030 012 697.92 40 40.6 53 104762 103609 013 nat.Mg 72 193259 175680 014 47 196758 181074 015 50 50.7 65 84642 83994 016 199188 186705 Summary table Mar. 19, 2009 the Spectrometer Group
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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 Mar. 19, 2009 the Spectrometer Group
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Data analysis: background treatment
ADC overflow of measured charge: which cause a pile- up at x = L/2 Mar. 19, 2009 the Spectrometer Group
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Data analysis: background treatment
QL, QR drifts caused by pre-amp resistance / ADC zero level: result in error on x calculation Mar. 19, 2009 the Spectrometer Group
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Data analysis: background treatment
Drift of PMTs of plastic E counter: 300 signal & BG not orthogonal 205 here Mar. 19, 2009 the Spectrometer Group
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Data analysis: background treatment
Drift of PMTs of plastic E counter: signal & BG orthogonal now Mar. 19, 2009 the Spectrometer Group
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Data analysis: background treatment
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Data analysis: ds/dW & DWBA cal.
Fresco: After BG reduction Statistic error only. Mar. 19, 2009 the Spectrometer Group
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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. Mar. 19, 2009 the Spectrometer Group
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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 Mar. 19, 2009 the Spectrometer Group
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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 Mar. 19, 2009 the Spectrometer Group
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Mar. 19, 2009 the Spectrometer Group
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Mar. 19, 2009 the Spectrometer Group
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Mar. 19, 2009 the Spectrometer Group
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Mar. 19, 2009 the Spectrometer Group
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Thank you A primer course of experimental nuclear and particle physics Osaka University, 2009
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Appendix: elastic term
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Appendix: detector arrangement
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Appendix: timing chart
Trigger DAQ system GDG FIFO VETO CCNET BUSY Mar. 19, 2009 the Spectrometer Group
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Appendix: excited states of 58Ni
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Appendix: ds/dW & DWBA calculation
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Appendix: ds/dW & DWBA calculation
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Appendix: ds/dW & DWBA calculation
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Appendix: ds/dW & DWBA calculation
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Appendix: ds/dW & DWBA calculation
Mar. 19, 2009 the Spectrometer Group
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