study of 58 ni excited states by (p, p’) inelastic scattering a primer course of experimental...

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

A primer course of experimental nuclear and particle physics

Osaka University, 2009

Mar. 19, 2009 the Spectrometer Group

Outline

Introduction Experiment

RAIDEN spectrometer Detectors, electronics & DAQ Online tuning

Data analysis State identification Differential cross section BG treatment Result

Summary Acknowledgements


Introduction: inelastic scattering

Inelastic scattering: (in a non-relativistic view)

at a given angle …

excitation states are measurable

elastic term excitation termobservable

xinout mEfEE 2

*


Introduction: spectrometer

Spectrometer = prism Distinguishes particles with

different momentum

Well designed magnets are required to guarantee precise measurement

Bp 2

pE -1<<1

xE in a small range


inelastic perturbation

elastic term

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

2|| iUfd

d

21 UUU

1U

2U


Experiment: overview

RAIDEN @ RCNP Proton beam at 53 MeV energ

y from AVF = 2.7 msr (slit), SWPC, p

lastic E-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


Experiment: RAIDEN @ RCNP

RAIDEN spectrometer: NIM 175 (1980) 335

Incredible: 30 years old but still works well!


Experiment: detectors

Single Wire Proportional ChamberNIM 196(1982)249; NIM 217(1983)441

Signals: • QL, QR position• E1, E2

• EL, ER, Time• EL, ER, Time • RF Time

Side view

BA

A

QQ

Q

L

y

“Charge Division”Ar+CO2 5%


Experiment: detectors

Plastic Scintillater

ex

IV

x

V


Experiment: targets


Experiment: electronics

Fast signals Slow signals

Busy-resistant logic

Coincidence logic


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


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)


On the other hand:

ρcorresponding

with x →Ex ~x

From data analysis

we get the position

spectrum of proton

(θ=150)


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

2+(145

4)

4+(246

0)

2+(303

8)

2+(326

5)

4+(362

1)

3-(4475)

4+(475

5)


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)


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.


Data analysis: run summary

runB [m

T]Brho [Tm]

[deg] [deg]

Tar I [nA] Trig Live Q [nC]

LAB C.M.

001 711.602 1.0674 15 15.2　 58Ni 20

Tuning runs002 690.613 1.0359 15 15.2　 58Ni 20

003 697.919 1.0469 15 15.2　 58Ni 2.25

004 697.93 1.0469 15 15.2　 58Ni 30 177270 171667 51408.5

005 697.93 1.0469 20 20.2　 58Ni 45 79053 76555 26160.2

007 697.93 1.0469 20 20.2　 58Ni 43 44468 43204 14723.0

008 697.93 1.0469 25 25.3　 58Ni 35 88817 86947 36346.0

010 697.93 1.0469 30 30.4　 58Ni 48-65 145175 141972 91920.8

011 697.93 1.0469 35 35.5　 58Ni 68 130913 129030 123316.7

012 697.92 1.0469 40 40.6　 58Ni 53 104762 103609 117726.8

013 697.92 1.0469 40 　 nat.Mg 72 193259 175680 30672.3

014 697.92 1.0469 25 　 nat.Mg 47 196758 181074 29770.8

015 697.92 1.0469 50 50.7　 58Ni 65 84642 83994 162986.1

016 697.92 1.0469 50 　 nat.Mg 65 199188 186705 47744.0

Sum

mary table


Data analysis: cross section calculation

Q

Ced , C: the count of the state, Q: the total charge of

incoming beam, the reduced density of target, e the charge of proton, the detecting efficiency, and the solid angle


Data analysis: background treatment

ADC overflow of measured charge: which cause a pile- up at x = L/2



QL, QR drifts caused by pre-amp resistance / ADC zero level: result in error on x calculation

LLL CQQ *

RRR CQQ *



Drift of PMTs of plastic E counter:

RPLLPLavePL EEE ,, here

signal & BG not orthogonal

300

205



Drift of PMTs of plastic E counter: signal & BG orthogonal now


Data analysis: d/d & DWBA cal.

Statistic error only.

After BG reduction

Fresco: http://www.fresco.org.uk/

http://www.fresco.org.uk/


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.


Summary

Nuclear reaction theory with Born approximation Determination of the angular momentum of excited s

tates Prepare of the target. Detection of charged particles with a single-wire pro

portional chamber and plastic scintillators and their operation.

Electric circuits and a CAMAC based data acquistion system

Data analysis, determination of differential cross section


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

Thank you

A primer course of experimental nuclear and particle physics

Osaka University, 2009


Appendix: elastic term


Appendix: detector arrangement


Appendix: timing chart

Trigger

DAQ system

GDG

FIFO

VETO

CCNET BUSY

CCNET BUSYGDG


Appendix: excited states of 58Ni


Appendix: d/d & DWBA calculation

study of 58 ni excited states by (p, p’) inelastic scattering a primer course of experimental...

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