Transcript 8th Topical Seminar on Innovative Particle and Radiation Detectors 1

8th Topical Seminar on Innovative Particle and
Radiation Detectors
Siena, 21 – 24 October 2002
1
SIENA is located in Tuscany
about 50km south of Florence
Ancient Etruscan settlement,
became Roman colony under the
name of Sena Julia
Its importance grew in Middle
Ages until became a municipality
in 12th century: flourished in XIV
century
Frequent confrontations with
neighbouring towns: taken over
by Florence in 16th century
Still retains an authentic medieval
2
atmosphere
Piazza del Campo 14th
century, is the heart of the
city
Location of the ancient
roman forum, boasts 14th
century gothic buildings
Palazzo pubblico e Torre
del mangia Fonte Gaia by
Jacopo della Quercia
The horse race (Palio) is held here, 2nd
of July and 16th of August
Of medieval origin, sees the 10
of the 17 contrade competing
against each other: the winner
gets the Palio (banner)
3
The Dome,XIV century: one of the
best roman-gothic architectural
examples
Masterpieces by Nicola
Pisano, Donatello,Pinturicchio
Floor consisting of 56 different mosaics,
depicting sacred scenes, required more
than 150 years to be completed
4
High Energy
Neutrino Astronomy
Christian Spiering,
Siena, October 2002
5
Physics Goals
A. High Energy Neutrino Astrophysics
Weakly interacting neutrinos reach us from very distant sources:
possible invaluable instrument for high-energy astrophysics
B. Particle Physics
Magnetic Monopoles, Oscillations,
Neutrino Mass ...
C. Others
Supernova Bursts, CR composition,
6
Black Holes, ...
Cosmic Rays
GZK cut-off
1 TeV
7
Supernova shocks
expanding in
interstellar medium
up to 1-10 PeV
Crab nebula
8
Active Galaxies:
accretion disk and jets
up to
20
10
VLA image of Cygnus A
eV
9
Air showers
Underground
Radio,Acoustic
log(E2  Flux)
Underwater
pp core AGN
p blazar jet
Top-down
WIMPs
Oscillations
GZK
GRB
Microquasars etc.
(W&B)
3
6
9
TeV
PeV
EeV
log(E/GeV)
10
Mannheim & Learned,
2000
Diffuse Fluxes:
Predictions and Bounds
Macro
Baikal
Amanda
9
1 pp core AGN (Nellen)
2 p core AGN
Stecker & Salomon)
3 p „maximum model“
(Mannheim et al.)
4 p blazar jets (Mannh)
5 p AGN
(Rachen & Biermann)
6 pp AGN (Mannheim)
7 GRB
(Waxman & Bahcall)
8 TD (Sigl)
9 GZK
11
Detection Methods
and Projects
Underwater/Ice Cerenkov Telescopes
Acoustic Detection
Radio Detection
Detection by Air Showers
12
Underwater/Ice Cerenkov Telescopes
Strings of widely spaced PMT put in deep water
AMANDA: Antarctic Muon
And Neutrino Detector Array
4-string stage (1996)
13
Cerenkov radiation in H2O : v0.75c,  = tg-1[(n2 v2/c2-1)1/2]
High-energy neutrinos through the earth may interact and
create muons which emit Cherenkov light
muon
cascade
14
SPASE air shower arrays
1 km
 resolution Amanda-B10 ~ 3.5°
results in ~ 3° for upward moving muons
(Amanda-II: < 2°)
2 km
15
AMANDA
80PMTs
302PMTs
Super-K
DUMAND
AMANDA-II
Amanda-II:
677 PMTs
at 19 strings
(1996-2000)
16
Point Sources Amanda II (2000)
1328 events
Preliminary limits (in units of 10-15 muons cm-2 s-1):
Cas A: 0.6 Mk421: 1.4 Mk501: 0.8 Crab: 6.8 SS433: 17
10.5
m  cm-2 s-1
southern
sky
northern
sky
10-14
170 days
AMANDA-B10
8 years
MACRO
10-15
-90
SS-433
Expected sensitivity
AMANDA 97-02 data
-45
0
45
declination (degrees)
Mk-421 / ~ 1
90
18
IceTop
IceCube
- 80 Strings
- 4800 PMT
- Instrumented
volume: 1 km3
- Installation:
2004-2010
AMANDA
South Pole
1400 m
2400 m
19
mediterraneum
Mediterranean
Projects
2400m
ANTARES
NEMO
3400m
4100m
NESTOR
20
Site: Pylos (Greece), 3800m depth
towers of 12 titanium floors each supporting 12 PMTs
21
40
Submarine cable
km
2400
m
22
ANTARES Design
Shore station
Optical module
10 strings
12 m between storeys
~60m
float
hydrophone
Compass,
tilt meter
2500m
Electro-optic
submarine cable
~40km
300m
active
Electronics containers
Readout cables
~100m
anchor
Junction box
23
Acoustic beacon
NEMO
Neutrino Mediterranean Observatory
abs. length ~70 m
80 km from coast
3400 m deep
24
NESTOR
1991 - 2000 R & D, Site Evaluation
Summer 2002
Deployment 2 floors
Winter
2003
Recovery & re-deployment with 4 floors
Autumn 2003
Full Tower deployment
2004
Add 3 DUMAND strings around tower
2005 - ?
Deployment of 7 NESTOR towers
ANTARES
1996 - 2000
2000
2001
September 2002
December 2004
2005 - ?
R&D, Site Evaluation
Demonstrator line
Start Construction
Deploy prototype line
10 (12?) line detector complete
Construction of km3 Detector
NEMO
1999 - 2001
2002 - 2004
2005 - ?
Site selection and R&D
Prototyping at Catania Test Site
Construction of km3 Detector
25
ACOUSTIC DETECTION
•Suitable for UHE Threshold > 10 PeV
•Particle shower  ionization  heat  perpendicular pressure wave
Maximum of emission at ~ 20 kHz
d
50ms
P
t
R
Attenuation of sea water
→ given a large initial signal,
huge detection volumes
can be achieved.
26
AUTEC array in Atlantic
existing sonar array for submarine detection
Atlantic Undersea Test and
Evaluation Center
52 sensors on 2.5 km lattice (250 km2)
4.5 m above surface
1-50 kHz !
27
RADIO DETECTION: Askaryan process
Interaction in ice:e + n  p + ee-  ... cascade
 relativist. pancake
~ 1cm thick,  ~10cm
 each particle emits
Cherenkov radiation
 C signal is
resultant of
overlapping
Cherenkov cones

Compton scattered electrons
shower develops negative net
charge Qnet ~ 0.25 Ecascade (GeV).
Coherent Cherenkov signal
for  >> 10 cm (radio)
 C-signal ~ E2
nsec
Threshold > 10 PeV
28
Showers in RF-transparent media (ice, rock salt)
RICE Radio Ice Cherenkov Experiment
firn layer (to 120 m depth)
20 receivers + transmitters
UHE NEUTRINO
   
DIRECTION
E 2 · dN/dE
< 10-4 GeV · cm-2 · s-1 · sr-1
at 100 PeV
300 METER DEPTH
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AntarcticImpulsiveTransientArray
Flight in 2006
30
Far inclined showers ( thousand per year)
• Flat and thin shower front
• Narrow signals
• Time alignment
Deep inclined showers (~ one per year?)
• Curved and thick shower front
• Broad signals
Extensive Air Showers
for E > 10 EeV produce
Ionization trails
el.-magn.
cascade
from e
hard
muons
from CR
31
Observation of upward going optical Cherenkov radiation
emitted by tau neutrino -induced air-showers
Need an observation from above (satellite)
32
Horizontal Air Showers seen by Satellite
E > 1019 eV
500 km
60 °
Mass up
to 10
Tera-tons
Horizontal
air shower
initiated deep
in atmosphere
1 - 20 GZK ev./y
Area up
to 106 km2
33
Extreme Universe Space Observatory
OWL
Orbiting Wide-angle Light-collectors
34
RICE
AGASA
GLUE
Amanda, Baikal
2002
AUGER t
2004
Anita
AABN
2007
EUSO
2012
km3
Auger
Salsa
35
Conclusions
0.1 km3 and 1 km3 detectors underwater and ice
Contacts: Christian Spiering [email protected]
36
Solar Neutrino Spectrometer
with InP Detectors
P.G. Pelfer
University of Florence and INFN, Firenze, Italy
F. Dubecky
Institute of Electrical Engineering, Slovak Academy of
Sciences
Bratislava, Slovakia
A.Owens
ESA/ESTEC
Noordwijk,Netherland
37
Why InP Solar Neutrino
Experiment ?
Semi Insulating InP Material
base material for:
Hard X-Ray Detectors
Fast Electronics and Optoelectronics
InP Spectrometer,
the Smallest, Real Time, Lower Energy
pp Solar Neutrino Spectrometer
The Solar Neutrino Spectrometer from/for R&D on InP X-Ray
Detectors ?
38
DETECTOR APPLICATIONS
• BASIC KNOWLEDGE
•
Solar Neutrino Physics
• X-ray astronomy
• X-ray physics
• MEDICINE
• Digital X-ray radiology (stomatology, mammography, ...)
• Positron emission tomography
• Dosimetry
• NONDESTRUCTIVE ON-LINE PROCESS CONTROL
• Material defectoscopy
• MONITORING
• Environmental control
• Radioactive waste management
• Metrology (testing of radioactive sources, spectrometry...)
• NATIONAL SECURITY
• Contraband inspections: cargo control
• Detection of drugs and plastic explosives
• Cultural heritage study
39
Requirements for Hard X-Ray
Detectors of the New Generation
>10keV
•
•
•
•
•
•
•
•
•
Room temperature (RT) operation
Portability
Fast reaction rate
Universal detection ability
Good detection parameters: CCE, FWHM,
DE
Radiation hardness
Well established material technology
Well established device technology (10
mm)
FE Electronics and Optoelectronics
integration on the Detector
RT OPERATION:
POLARISATION EFFECT:
HIGH ENERGY RESOLUTION:
HIGH STOPPING POWER:
HIGH CARRIER MOBILITY:
cm2/Vs
EG > 1.2 eV
EG < 2.5 eV
EG small
Z > 30
> 2000
CANDIDATES
CdTe, HgI2, GaAs, InP
• LOW COST
40
Attenuation and mobility
41
Neutrino from the
Sun
Water
Kamioka, SuperK
x + e-  x + e- (ES)
Gallium
SAGE, Gallex, GNO
e + 71Ga  71Ge + eChlorine
Homestake
e + 37Cl  37Ar + eD2O
SNO
x + e-  x + e(ES)
e + d  p + p + e(CC)
x + d  n + p + e(NC)
42
43
Requirements for Indium Solar Neutrino
Spectrometer
1. Indium incorporated into the detector
2. Energy resolution ∆E/E of the order of 25% at 600 keV.
Important for spectrometry as well as background reduction.
3. Time resolution of the order of 100 ns for ~ 100 keV radiations.
4. Position resolution ∆V/V  10-7 at a reasonable cost. Very
important
for background reduction
5. Good energy resolution for low energy radiations ( ~ 50 keV )
6. Made with materials of high radiactive purity
44
Neutrino Detection by In Target
t1/2= 4.76 m sec 7/2 612.81 keV
e
+
1
3/2+ 497.33 keV
9/2+
115In
(95.7%)
t1/2
=6x1014
y
-
2
1/2+ 0
115Sn
E    e(E - 118 keV ) + 115 Sn* 
 Delay t = 4.76 m sec 
 115Sn*  115Sn + e-(88  112 keV)/1 (115.6 keV) + 
2(497.33 keV)
45
“ delayed event “
in a 27 cm3
macrocell
" prompt event
“ in a “1 cm3
cell”
3
2
4
3
4
2
1
9
8
5
1
5
1
Solar Neutrino Event
in InP Detector
2
6
7
6
e
9
8
7
1 cm3 cell
Detector made
up of many
‘basic cells’
106 InP “1 cm3 cell”
Calorimeter Module
46
FULL NEUTRINO
SPECTROMETER
Spectrometer Building Block
Nmodules  125
Spectrometer Module
100 mm
200 mm
Pad Detectors
V microcell  1
mm3
N microcell /cm3 
1000
1 neutrino event once a day
for 1011 background events
47
Present InP Material and Detector
Technology
SemiInsulating InP Wafer
6” diameter, 1 mm thick
Basic Component of
Neutrino
Spectrometer
Pad Detectors
48
SI InP Material and Detector Technology
Producer:
JAPAN ENERGY Co., Japan
Growth Technique:
LEC
High-Temperature Wafer
Annealing
Resistivity (300 K):
cm
4.9x107
Hall Mobility (300K):
4410
Fe Content:
2x1015
Orientation:
<100>
cm2/Vs
cm-3
Final Wafer Thickness: ~ 200 mm
Original BUFFERS realised using
ion implantation in backside
(PATENTED)
Symmetrical circular contact
configuration, 2mm  , using both-sided
photolithography
Final metallisation: TiPtAu on top and
AuGeNi on backside
Surface passivation by Silicon Nitride
49
InP Detector Test Setup
3.142 mm2 x 200 mm
50
Energy Resolution vs Shaping Time and
Spectral Response in InP Laboratory Measurements
E=2.4 keV at 5.9 keV : 8.5 keV at
59.54 keV
51
Linearity and Resolution vs X Ray Energy
in InP Laboratory Measurements
E  2.355 FE  e / 2.355  a1 E
2
a2
52
InP Spatial Distributions
The detectors spatial response measured at
HASYLAB using a 50  50 mm2, 15 keV Xray beam.
bond wire
contact
Count rate
Peak centroid
Resolving
power
53
Summary and Conclusions
Present Radiation Detectors based on Bulk SI InP Fe doped
have very good Detection Parameters
for the X ray Detection
from HASYLAB SR Facilty
FWHM from 2.5 KeV at 5.9 KeV to 5.5 KeV at 100 KeV
DE 10% at 100 KeV for 200 mm thick Detector
due
to Better Material from Japan Energy
and to Improved Interface Technology
Some Problems for Detector Polarisation
Detectors performances good for Solar Neutrino Spectrometer
Optimisation is our next research goal
Contacts: Pier Giovanni.Pelfer [email protected]
54
Application of nanotechnologies
in High Energy Physics
A.Montanari, F.Odorici
INFN Bologna & Bologna University
Italy
55
•Nanotechnologies characteristics
•Technologies for processing material on a nanometric scale:
1-100nm
•Interests in many field of research: biology, chemistry,
nanoelectronic,science of material
Nano-objects very attractive also in terms of application to a
new generation of position particle detectors
Nano-holes, nanochannels
Nano-wires, nanotubes
Mask, dies
Contacts, probes
56
Nanotubes introduction
•Single-Wall Carbon Nanotubes (SWNT) discovered in 1991
•Essentially long thin cylinders of carbon
57
•Single-wall nanotubes are formed in a carbon arc in the presence
of a metal catalyst. The tubes are found in the matted soot
deposited on the reaction chamber wall
low yield
•The As-Produced Soot contains tubes that are 0.7-1.2 nm in
diameter and 2-20 µm in length. The product contains 10-40%
tubes, the remainder is carbon-coated metal nanoparticles and
amorphous and carbon nanoparticles
price list from Bucky USA website
[email protected]
58
•NT can have very broad range of electrical, optical,
mechanical, thermal characteristics depending on their
geometrical properties (diameter, length and chirality)
•SWNT are truly 1D objects
•Beside SWNT it is possible to grow Multiple Walls Nano Tubes
(MWNT)
Energy gap dependency
on diameter and chirality
Quantum conductance of MWNT
G0 = 2e2/h 1/12.9 k -1
59
NT applications
•Nanotransistor FET using NT as channel
Microphotograph
from IBM website
•At low temperature, it becomes
a Single Electron Transistor
(SET)
60
FIELD EMISSION FROM ARRAYS OF CARBON NANOTUBES
The aligned Nanotube field emitter are grown on a silicon substrate, by CVD
Nanotubes array grown by CVD
20m left 2 m right 1 m separation min
from NanoLab website
61
•Peculiar properties expected by the
nanodimensions associated with NT filling:
•Superconductive phenomena (reported for K,Rb,Cs)
at rel. high temp 50K
TEM image of
KI@SWNT hybrid
material
2 atoms crystal KI within 1.4nm SWNT
62
•New concept: bundles of NT used for position
detectors
Radiation
Readout
electronics
•Filling of nanotubes already possible
Nanopixel detector
63
•Require uniform and reproducible structure:
using catalysts in chemical vapour deposition
straight nanotubes are possible
Anodization of iperpure Aluminum
sheets (100-300 mm thick ) under
controlled conditions produces an
oxide (Al2 O3 , Alumina) with
self-organized regular honeycomb
structure
The size and pitch of nanochannels
depend on the parameters of the
process (voltage, acid type,
acid concentration, temperature):
Pitch: 40 -> 400 nm
64
 Alumina nanochannels used to grow nanotubes
Alumina nanochannels can be used to grow CNs,
after the
deposition of the catalyst (Ni, Fe, Co) at the bottom of
each single pore
Growth of CN by Chemical Vapor Deposition of a
hydrocarbur at 600- 800 o C
Temperature, gas concentration and duration of the
process determine the CN structure (SWNT or MWNT,
metallic or semiconductor)
65
Alumina nanochannels growing
66
NANO CHANNEL ACTIVE LAYER DETECTOR CONCEPT
67
Conclusions
 NanoChant project (INFN & CNR) started as an R&D study aimed at
improving by one order of magnitude the spatial resolution of position
particle detectors, by using nanotechnologies (Carbon Nanotubes grown
inside Alumina Nanochannels)
• Present state: building of the Alumina Nanochannels pore size 40nm
pitch 100nm
• Immediate next step: growing of CN inside Nanochannels
• Future step: study of properties of CN, to optimise their use as charge
collectors and their coupling to active medium
Contacts: [email protected]
68
Resistive Plate Chambers as
thermal neutron detectors
DIAMINE Collaboration
WP-2 BARI, Italy
M. Abbrescia, G. Iaselli, T. Mongelli,
A. Ranieri, R. Trentadue, V. Paticchio
69
Reasons for new thermal neutron
detectors
The humanitarian demining problem
Metal Detectors not effective
against anti- personnel
mines:
Neutron Backscattering
Technique (NBT)
•Neutron backscattering method: moderation of high-energy neutrons
produced by radio-isotopic source or generator
70
• Low (thermal) energy neutrons reflected from the soil is a direct
indication of the amount of hydrogen
• The amount of hydrogen in a plastic landmine is much higher (40-65%)
than that of the surrounding soil even in case this is wet
• A thermal neutron detector in combination with a neutron source is
scanned across the soil, the presence of a landmine will be indicated by an
increase in the number of thermal neutrons
Cosmics
252Cf
source
RPC
Thermal n
 and “fast” n
Ground
Landmine
71
RPCs for thermal neutron detection
1) Bakelite electrodes
2) Gap: 2 mm
3) HV electrodes: graphite 100 mm
4) High resistivity layer
5) Pick-up strips
6)&7) readout electronics
Operating pressure: ~ 1 Atm
bakelite resistivity 10 10- 10 12 cm
electrodes treated with linseed oil
RPCs are easy to build, mechanically robust, light-weighted, cheap, can
cover large surfaces, are adapt for industrial production, etc.
72
particularly suitable for “on-field” applications
Neutron Detection
Neutrons can be
revealed only
after the interaction
in a suitable material
Production of
secondary ionising
particles
The choice of the
converter is crucial for
the performance of the
detector73
Choice of the converter
Gd
• Natural Gd is characterized by a thermal neutron  (50
kbarn) 12 times larger than 10B  (3840 barn)
• Produced electron range (15-30 mm) is >than ’s (3-4 mm)
• Beyond E=100 meV, Gd cross section decreases much more
rapidly than the one of 10B E1 eV it is smaller than the one of
10B.
For application concerning only thermal neutron detection Gd
is preferable to 10B
74
• Layer of the converter consists of Gd2O3
mixed with linseed oil; the mixture is
sprayed onto the bakelite electrodes, which are used to build standard RPC
•
It is possible to obtain extremely uniform layers, with very constant thickness
and density
HV
Gas
• RPCs 10x10 cm2 in dimensions one without Gd2O3, used
as a reference and two with a different concentration
of the oil Gd2 O3 mixture
• Signal readout: copper pad Signal input to: NIM discriminator,
Vthr=30
• Operating voltage 10-11kV (streamer mode) gas mixture
The electric properties (surface resistivity) of bakelite electrodes are not altered
75
Schematic diagram of test system
2 layers of
0.35μm
eU
C
I
10B
RPC with Gdoil
R
P
C
t0 start DAQ
T
D
C
1
T
D
C
2
tn stop to a multihit TDC
TOA of e- plus delay start signal for two multihit TDC
computed
Neutron energy
76

‘raw’ data show already the higher efficiency achieved using this method
•Background noise (of the chamber, out of time
neutrons) to be taken into account
Relative efficiency of
conversion:
N
 
N
RPC
rel
CI
around 2.5-3
times better
77
Conclusions
•Demonstrated the feasibility of this approach to build Gd-RPC for thermal neutrons
•Both detectors have an efficiency > 2.5 eff. CI ( 6%)
•RPC-Gd experimental efficiency is > 10B theoretical maximum efficiency
>>
10B-RPC
experimental efficiency
•Coupling two of these detectors together efficiency reaches
about 3.5-4 eff. CI (analysis in progress)
•Performances of various types of detectors have been
evaluated by a technical board of EC together with
Monte Carlo analysis of the signal generated by a APL.
•Decision on when and how to really test a device is
being under consideration.
Contacts: [email protected]
78
ADVANCES IN SEMICONDUCTOR DETECTORS FOR
PARTICLE TRACKING IN EXTREME RADIATION
ENVIRONMENTS
Cinzia Da Via’
Brunel University, London, UK
79
INTRODUCTION
PHYSICS REQUIREMENTS AT LHC AND SHLC (1035 cm2s-1)
p
p
b
H
Higgs channel
b
SUCCESS OF THE EXPERIMENTS
REQUIRE PRECISE MEASUREMENT OF
•MOMENTUM RESOLUTION
•TRACK RECONSTRUCTION
•B-TAGGING EFFICIENCY
POSSIBLE WITH SILICON, HOWEVER…
80
RADIATION ENVIRONMENT AT LHC AND
EXPECTED AT SLHC
5*1015  5*1014
81
PRESENT STATUS OF RAD HARD
SILICON DETECTORS NORMALLY USED IN HEP
82
EFFECTS OF RADIATION DAMAGE IN SILICON DETECTORS
•Generation of charge traps by displacement damage of bulk silicon (interstitials and
vacancies)
•Nuclear interactions
•Secondary processes from energetic displaced lattice atoms
Non Ionizing Energy Loss:
Energy loss due to collision with lattice
nuclei
• depends on mass of the particle
83
RADIATION INDUCED BULK DAMAGE
84
RADIATION DEFECTS AND MACROSCOPIC EFFECTS
V,I mobile migrate until meet
impurities and dopants
to form stable defects:
•Charge defects: Neff,Vbias
•Deep traps, recombination
centers: signal charge loss
•Generation centers: Ileak noise
Oxygen-Vacancy complex forms an
acceptor state in the upper half of
band-gap (acts as a trapping
center)
Neff
85
MACROSCOPIC PARAMETERS CHANGES AT 1015 n/cm2
86
SPACE CHARGE AFTER IRRADIATION
87
COLLECTION DISTANCE DETERMINED BY DRIFT LENGTH
Leff= tt*Vdrift
•Also effect of charge sharing due to low field region after type
inversion
88
MAIN DETECTORS STRATEGIES FOR SURVIVAL BEYOND 1015 n/cm2
89
OXYGEN AND STANDARD SILICON
•Defect engineering:influence the defect kinetics by incorporation of impurities
•Higher O content: less donor removal
•Vfd reduced 3 times
•No improvements for neutrons
O
VO not harmful @ room T
V
P
VP donor removal
90
SHORT DRIFT LENGTH USING 3D DETECTOR
91
3D VERSUS PLANAR APPROACH
92
CONCLUSIONS:
Contacts: [email protected]
93
Analysis and Simulation of Charge
Collection in
Monolithic Active Pixel Sensors (MAPS)
E.Giulio Villani, Renato Turchetta, Mike Tyndel
Rutherford Appleton Laboratory
94
MAPS CONCEPTS AND CHARACTERISTICS
RC
eo
an
dt
or
uo
t l
Reset
Column
line
Row sel
Column parallel ADCs
Data processing – output
stage
I2 C
•Charge generated by impinging radiation in sensitive element D diffuses towards the cathode.
The related voltage variation is buffered by the source follower and transmitted further down the
line once the row is selected. One row at a time is readout
95
electronics
P+
N+
P Sensitive volume
(2 – 20 μm thick)
P++ Substrate
(300 – 500 μm thick)
P+





•Ionisation- generated charge remains confined within the potential well in the
epitaxial layer and moves by thermal diffusion towards the cathode
96
Typical results
tF  20ns
•Typical diffusion time for 5mm active area is about 20ns, with 600e- collected (simulation
performed with ISE-TCAD on device with 5mm epitaxial thickness >10mm substrate 2V bias)
Sufficiently fast for Linear Collider: however, LHC would require faster and more radiation tolerant
device
97
New concept design and analysis: introduction of N-layer to extend
electric field into active region
Active area
Cathode
N layer
 2


z 2  Si o
n  D 2n  G  R
n
n n
t


 ( z) q N D 


E
 Fn  E Fi

 N  n exp
A
i

KT

To be solved within
the regions of the
device
 E E

 Fi

Fp
  n exp

i

KT



98






DEVICE DESIGN
Simulation results: Electric field comparison
NEW
STANDARD
99
Superposition of voltage variations at the collecting cathode: new
structure shows smaller swing than the standard structure but is
faster regardless of the hit point
τF 2ns
τF
17ns
Fall time τF (0 to 90% of full swing) approximately 8.5 times smaller
100
NEW
STANDARD
τF  2ns
Charge collection time shows the same fast behavior with fall time τF  2ns
Total capacitance C  6.63fF
101
CONCLUSIONS
•
Results of 2D simulations on standard MAPS compare favorably
with what amply reported in literature
•
New structure proposal: analysis suggests the possibility of
performances improvements
•
Design and simulation: results show shorter collection time and
better efficiency which pave the way for improved radiation tolerance
Next steps:
o
Full 3D simulation of a device with side implants
o
Fabrication and test
o
Implementation of readout electronics
102
New device structure
X
Y
Z
DSUB
PWx
DNWy
PWy
103