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UNIVERSITI PUTRA MALAYSIA
LOJIUS BIN LOMBIGIT
FK 2012 16
DEVELOPMENT AND CHARACTERIZATION OF READOUT ELECTRONICS FOR NEUTRON SCATTERING INSTRUMENTATION
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DEVELOPMENT AND CHARACTERIZATION OF READOUT
ELECTRONICS FOR NEUTRON SCATTERING INSTRUMENTATION
By
LOJIUS BIN LOMBIGIT
Thesis Submitted to the School of Graduate Studies, Universiti Putra
Malaysia, in Fulfilment of the Requirements for Degree of Master Science
May 2012
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DEDICATIONS
Dedicated to my beloved wife & son
Rollyne Alip & Luke Ryan Lombigit
for their endless support
My parent,
Late Abel Lombigit Bolukis and Rubeca Ladom
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Abstract of thesis presented to the Senate of Universiti Putra Malaysia
In fulfilment of the requirement for the degree of Master of Science
DEVELOPMENT AND CHARACTERIZATION OF READOUT
ELECTRONICS FOR NEUTRON SCATTERING INSTRUMENTATION
By
LOJIUS BIN LOMBIGIT
May 2012
Chair: Associate Professor Mohd. Nizar Bin Hamidon, PhD
Faculty: Faculty of Engineering
In the field of material characterization, the neutron scattering technique is
found to be useful in many applications. This technique requires a position
sensitive neutron detector (PSND) and their readout electronics to detect the
position of neutron interactions. Fast, high count rate and high positional
resolution PSND such as the 3He-filled Multi-Wire Proportional Counter
(MWPC) is designed for specific applications and has unique technical
specifications. Therefore, it requires customised readout electronics which
capable of accepting a wide range input signal, good noise/ENC performance
or fast signal processing to match their specifications. In order to optimize
the detector’ performance in terms of speed, count-rate, and positional
resolution, the individual readout method is often employed as positional
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encoding method to detect the neutron interactions. In this method, each
wire are connected to an individual readout electronic and if the applications
requires large active area detector, a large number of readout electronics are
required thus, increased the development cost. This study presents the
design and development of readout electronics comprise of an eight (8)
channels low noise charge sensitive preamplifier-pulse shaping amplifier
(CSP-PSA) chain capable of accepting a wide range input signal and fast
signal processing which is ideal for high count rate and high position
resolution neutron scattering instrumentations.
The readout electronic circuit is built entirely with low-noise FET-input
operational amplifier (Op-amp) and passive components. The time constant
for charge sensitive preamplifier (CSP) is around 250 ns and it is equipped
with an additional T-network at output stage. The pulse-shaping amplifier
(PSA) is designed based on a fifth-order complex-pole semi-Gaussian filter;
comprising a cascade first-order high-pass filter (HPF) with pole-zero (PZ)
cancellation networks and two second-order Sallen-Key low-pass filters (SK
LPF). These circuits are designed using Laplace transform then verified with
macro model component-based simulation. A series of testing had been
carried out to measure how well the actual performance fulfilled the major
objective. These procedures include measurements of direct-current (DC)
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offset, dynamic range, gain, linearity, electronic noise and analysis of time
over threshold (TOT).
The development cost of the readout electronics is around U.S $50/channel,
which is suitable for low-cost applications. Results showed that the readout
electronics has good electronic noise with measured Equivalent Noise
Charge (ENC) average at 2108 e- ± 10% and insensitive to input capacitance
variation (25 e-/pF). Charge calibration using the TOT method shows that it
can separate small difference of charge and capable of accepting a wide
dynamic range input charge (20-600 fC) with excellent linearity (nonlinearity
< 1%). Fast peaking time around 300 ns and short pulse width around 1.2 -
1.6 us, shows that it can be used for fast detector with count rate capability
below 50 kHz at 10% dead time.
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Abstrak tesis yang dikemukakan kepada Senat Universiti Putra Malaysia
sebagai memenuhi keperluan untuk ijazah Master Sains
PEMBANGUNAN DAN PENCIRIAN LITAR PEMBACA-KELUAR
ELEKTRONIK UNTUK INSTRUMENTASI PENYERAKAN NEUTRON
Oleh
LOJIUS BIN LOMBIGIT
Mei 2012
Pengerusi: Profesor Madya Mohd. Nizar Bin Hamidon, PhD
Fakulti: Fakulti Kejuruteraan
Dalam bidang pencirian bahan, teknik penyerakan neutron didapati sangat
berguna dalam pelbagai aplikasi. Teknik ini memerlukan pengesan neutron
peka kedudukan (PSND) dan juga litar pembaca-keluar elektronik yang
khusus untuk mengesan kedudukan tindakbalas neutron tersebut berlaku.
Pengesan yang mampu mengesan tindakbalas neutron pada kadar yang
pantas serta kadar bilang dan peleraian kedudukan yang tinggi seperti
pembilang berkadaran berbilang dawai (MWPC) yang diisi dengan gas 3He
biasanya direkabentuk untuk aplikasi tertentu dan mempunyai spesifikasi
teknikal yang unik. Oleh itu, ia memerlukan sebuah litar pembaca-keluar
elektronik yang berupaya untuk menerima isyarat masukan pada julat yang
besar, prestasi hingar elektronik/ENC yang baik atau mampu memproses
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isyarat pada kadar yang pantas. Kaedah mengekod kedudukan dengan
menggunakan teknik pembaca-keluar individu digunakan bagi
mengoptimakan keupayaan pengesan jenis MWPC tersebut. Dalam kaedah
ini, setiap dawai dalam pengesan MWPC perlu disambungkan kepada litar
pembaca-keluar elektronik secara individu. Sekiranya aplikasi tersebut
memerlukan pengesan dengan kawasan aktif yang luas maka litar pembaca-
keluar elektronik dalam kuantiti yang banyak akan diperlukan dan ini akan
meningkatkan kos untuk pembangunan peralatan tersebut. Kajian ini
mengemukakan sebuah rekabentuk dan pembangunan lapan saluran (8-
channels) litar pembaca-keluar elektronik berhinggar rendah yang dibina
dengan rantaian pra-penguat jenis peka-cas dan penguat pembentuk denyut
(CSA-PSA chain). Ia mampu menerima isyarat masukan pada julat dinamik
yang luas serta berkeupayaan untuk memproses isyarat tersebut pada kadar
yang pantas dan sesuai digunakan dalam peralatan serakan neutron yang
memerlukan kadar bilang serta peleraian kedudukan yang tinggi.
Litar pembaca elektronik ini dibina sepenuhnya dengan menggunakan
penguat kendalian (Op-Amp) jenis peranti masukan FET berhingar rendah
sebagai komponen aktif utama dan komponen pasif seperti perintang dan
pemuat. Litar pra-penguat jenis peka-cas (CSP) direkabentuk dengan
pemalar masa sekitar 250 ns dan ia dilengkapi dengan rangkaian-T
tambahan di peringkat keluaran. Manakala penguat pembentuk denyut
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(PSA) adalah daripada penapis jenis separa-Gaussian kutub-kompleks tertib
ke-5 yang dihasilkan daripada gandingan lata satu penapis laluan tinggi
tertib pertama (HPF) yang dilengkapi dengan rangkaian pembatalan kutub-
sifar (PZ) dan dua penapis laluan rendah tertib ke-2 jenis Sallen-Key (SK
LPF). Litar ini telah direka dengan menggunakan Jelmaan Laplace kemudian
disahkan dengan simulasi litar berasaskan komponen model-makro.
Beberapa siri ujian telah dijalankan untuk mengukur sejauh mana prestasi
sebenar litar pembaca-keluar tersebut dapat memenuhi objektif utama kajian
ini. Pengujian ini termasuk pengukuran ofset arus terus (DC offset), julat
dinamik isyarat masukan, gandaan serta kelurusan keluaran, magnitud
hingar elektronik dan analisis masa atas ambang (TOT).
Kos pembangunan bagi litar pembaca-keluar elektronik tersebut adalah
murah, sekitar USD50/saluran, oleh itu ia sesuai untuk aplikasi yang kos-
sensitif. Keputusan pengujian menunjukkan bahawa ia mempunyai prestasi
hingar elektronik yang baik dengan purata cas setara hinggar elektronik
(ENC) sekitar 2108 e- ± 10% dan kurang sensitif terhadap perubahan
kemuatan masukan (25e-/pF). Penentukuran cas dengan menggunakan
kaedah analisa TOT menunjukkan bahawa litar pembaca-keluar elektronik
tersebut dapat mengasingkan perbezaan kecil cas serta mampu menerima
cas masukan pada julat dinamik yang luas (20-600 fC) pada kelurusan yang
sangat baik (ketaklelurusan <1%). Denyut keluaran yang dihasilkan oleh litar
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tersebut mencapai puncak sekitar 300 ns manakala lebar denyut isyarat
keluaran adalah singkat sekitar 1.2 – 1.6 μs, ini menunjukkan bahawa ia
boleh digunakan untuk pengesan PSND yang pantas dengan keupayaan
kadar bilang di bawah 50 kHz pada masa mati sekitar 10%.
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ACKNOWLEDGEMENTS
Thanks GOD almighty who gives me the blessing, good health and wisdom
to complete this Master research.
I would like to take this opportunity to express my deep gratitude to my
supervisor Dr. Mohd. Nizar Hamidon. His assistance, encouragement, and
guidance are endless in every stage of this research. Thanks also to my co-
supervisor Dr. Mohd Ashhar Hj. Khalid and Dr. Nasri Sulaiman for the
invaluable suggestions and technical inputs during the past two years.
Other than that, I would like to express my thanks to my wife who always
support me mentally and physically. I am also thankful to my colleagues at
Malaysian Nuclear Agency for theirs assistance during experimental testing
and PCB design.
I am grateful for being part of the UPM family. I truly thank UPM for
providing all the necessary facilities to help me to complete this study.
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APPROVAL
I certify that a Thesis Examination Committee has met on 18 May 2012 to
conduct the final examination of Lojius bin Lombigit on his thesis entitled
“Development and Characterization of Readout Electronics for Neutron
Scattering Instrumentation” in accordance with Universities and University
College Act 1971 and the Constitution of the Universiti Putra Malaysia
[P.U.(A) 106] 15 March 1998. The committee recommends that the student be
awarded the Master of Science.
Members of the Examination Committee are as follows:
Suhaidi Bin Shafie, PhD
Senior Lecturer
Faculty of Engineering
Universiti Putra Malaysia
(Chairman)
Maryam Binti Mohd Isa, PhD
Senior Lecturer
Faculty of Engineering
Universiti Putra Malaysia
(Internal Examiner)
Izhal Bin Abdul Halin, PhD
Senior Lecturer
Faculty of Engineering
Universiti Putra Malaysia
(Internal Examiner)
Sahbudin Bin Shaari, PhD
Professor
Institute of Microengineering & Nanoelectronics (IMEN)
Universiti Kebangsaan Malaysia
(External Examiner)
SEOW HENG FONG, PhD
Professor and Deputy Dean
School of Graduate Studies
Universiti Putra Malaysia
Date: 27 August 2012
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This thesis was submitted to the Senate of Universiti Putra Malaysia and has
been accepted as fulfilment of the requirement for the degree of Master of
Science. The members of the Supervisory Committee were as follows:
Mohd. Nizar bin Hamidon, PhD
Associate Professor
Faculty of Engineering
University Putra Malaysia
(Chairman)
Mohd. Ashhar bin Hj. Khalid, PhD
Deputy Director General (Technical Service Programme)
Malaysian Nuclear Agency
(Members)
Nasri Sulaiman, PhD
Senior Lecturer
Faculty of Engineering
University Putra Malaysia
(Members)
BUJANG BIN KIM HUAT, PhD
Professor and Dean
School of Graduate Studies
Universiti Putra Malaysia
Date:
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DECLARATION
I declare that the thesis is my original work except for quotations and
citations which have been duly acknowledged. I also declare that it has not
been previously, and is not concurrently, submitted for any other degree at
Universiti Putra Malaysia or at any other institutions.
____________________
LOJIUS LOMBIGIT
Date: May 2012
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TABLE OF CONTENTS
Page
DEDICATIONS ii
ACKNOWLEDGEMENTS x
APPROVAL xi
DECLARATION xiii
LIST OF TABLE xvi
LIST OF FIGURE xvi
LIST OF SYMBOLS xx
LIST OF ABBREVIATIONS xxii
CHAPTER
1 INTRODUCTION 1
1.1 Research background 1
1.2 Problem Statement and Motivation 3
1.3 Research Objectives 4
1.4 Outline of Thesis 5
1.5 Scope of Work 5
2 LITERATURE REVIEW 7
2.1 Introduction 7
2.2 Detector for Neutron Scattering Instrumentation 8
2.3 Electronic For Neutron Detection 15
2.3.1 Preamplifiers 15
2.3.2 Pulse Shaping Amplifier (PSA) 19
2.3.3 Pole-Zero Cancellation 26
2.4 Requirements and Characterisation of Readout Electronic
Output Signal 28
2.4.1 Electronic Noise 30
2.4.2 Other Properties of Readout Electronic Output Signal 36
3 READOUT ELECTRONICS DESIGN 38
3.1 Overview 38
3.2 Charge-Sensitive Preamplifier (CSP) Design 39
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3.3 The Pulse-Shaping Amplifier (PSA) 41
3.4 Power Supply/Motherboard 48
3.5 Circuit Simulation 50
3.6 Printed Circuit Board (PCB) Design 52
3.7 Summary 54
4 OUTPUT PULSE CHARACTERIZATION 56
4.1 Overview 56
4.2 DC Offset Measurements 57
4.3 Dynamic Range, Charge Sensitivity and Output Linearity 58
4.4 Electronic Noise Measurement 59
4.5 Time over Threshold (TOT) Analysis 63
4.6 Summary 65
5 RESULTS AND DISCUSSION 66
5.1 Overview 66
5.2 The Readout Electronics (UPM-MNA-RENA) 66
5.3 Characteristics of the Output Signal 67
5.4 DC offset measurement 70
5.5 Dynamic Range, Charge Sensitivity and Output Linearity 71
5.6 Noise Measurement 75
5.7 TOT Analysis 80
5.8 Summary 83
6 CONCLUSION AND FUTURE RECOMMENDATIONS 84
6.1 Conclusion 84
6.2 Future Recommendations 85
REFERENCES 87
APPENDICES 95
BIODATA OF STUDENT 158
LIST OF PUBLICATIONS 159