UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Applications of
Silicon Detectors
Motivation
Principle of Operations
The Rise of Silicon Detectors
Applications
Charged Particle Tracking
Photon Detection
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Precision Particle Tracking Detectors
In Particle Physics, many new phenomena tend to be associated with heavy quarks.
• The Higgs search will depend on tagging heavy flavor jets,
• CP violation is being measured in the b system.
• Heavy quarks have a finite life time t, and can be identified by the decay length in the
lab Dz  gbct (= 250um in BaBar).
Primary
Z Vertex
Detached Vertexes
In B and anti-B
Vertexing precision depends on:
•distance of the detectors from the interaction point,
•the lever arm, and the
•intrinsic position resolution
of the detector
This requires detectors in close proximity (few cm) of the beams
with an intrinsic position resolution of 10 - 25um.
High particle densities in “jets” require fast, fine-grained detectors.
This is possible only with semiconductor detectors.
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Particle Tracking Detectors for Theorists
Choose a fine-grained detector to localize charged particles:
Passing of particle leaves a trail of temporal ionization (>10,000e) (see next)
Take advice from your local guru and collect it electronically
-> apply electric field, record tiny current Is (<uA in 10 ns) = signal
Problem: Resistivity of detector material : In = V/R gives large current
Way out: block current with capacitor
Problem: large current still gives background noise ~  In
Ways out:
Ultra-high resistivity materials (Diamonds, SiC, few Mohm-cm)
Reverse biased diode on Si (few kOhm-cm, industry grade)
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Electrostatics of Silicon Strip Detectors
Resistivity given by concentration of dopants N (donors or acceptors)
.
Charge can’t be collected from the conductive bulk :
have to deplete it of mobile carriers (e), leaving the bulk charged
Depletion depth depends on bias voltage
W
Capacitance measured the depletion depth
1/C2
VBias
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Dynamics of Silicon Strip Detectors
Charge Collection: Drifting Charges Induce Charges on Electrodes
Drift Velocity
E operating field, m mobility
Induced Charges
Vql : Weighting Potential (Ramos, 1937)
Signal Current due to drifting charges
ik = -qm E(x)•Fk(x)
Collection Time Scale
Signal ends when charge arrives at the strip
Fk(x) : Weighting Field (Cap)
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Further Reading for the Curious
http://britneyspears.ac/lasers.htm
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Signal in Tracking Detectors
Charged Particle Energy Loss
(aka Stopping Power, Linear Energy Loss LET)
Bethe-Bloch
~1/b1.5
measure p
Signal-to-Noise Ratio:
Signal ~ Thickness
Noise ~ Area, 1/ts
Rad
MIP
Directional Information
compromised by
Multiple Scattering
Multiple Scattering angle
-> Thin, low z materials
-> Improves at High Energy
Radiation Length Xo
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Properties of Silicon Strip Detectors
Reverse Bias of junction:
only thermal current generation
Scale : Band gap 1.12eV vs. kT = 1/40eV: huge Boltzmann factor
Cooling needed only in ultra-low noise applications.
Wafer thickness 300um = 0.3%RL:
23k e-h pairs
Depletion Voltage ~ thickness2 :
<100V
Readout electronics
Collection Time of e-h pairs:
~20ns
(S/N typically > 20)
Area is given by wafer size: 4” & 6” => Ladders
25-200 mm
Al
p+ implant
at ground
n+ implant
Al
at ~ 100V
SiO2
holes
Depletion region. Charged particle
traversing region produces ~80
electron/hole pairs per micron.
300-400 mm
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Evolution of Silicon Detectors
Large Area
Double-sided
Si Drift
3-D
n
Hybrid
Pixels
p
n
Monolythic:
CCD, MAP
n
n
p
n
n
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
The Rise of Silicon Detectors
Development of Area of SSD and # of Electronics Channels
follow Moore’s Law
Larger - CMS 10M Channels, 230m2
Faster - ATLAS 22ns
Cheaper - CMS ~$5/cm2
1000
2
Silicon Area [m]
o
GLAST
: SCIPP
O
10
NOMAD
LEP
D0
AMS-01
oo o
4
ATLAS
AMS-02
Agile
1000
D0
MEGA
100
o
GLAST
BaBar AMS-02
CDF
CDF
AMS-01 Agile
LPS
MEGA
NOMAD Pamela
Mark2
LPS
Mark2
CDF
LEP
BaBar
0.1
CMS
ATLAS
# of Electronics
Channels [in k]
CMS
o
100
1
10
10
CDF
Pamela
WIZARD
0.01
1985
1990
1995
Year
2000
2005
1
2010 1985
1990
1995
Year
2000
2005
2010
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
The Rise of Silicon Detectors
Area [m2]
Limited Resources (Power)
in Space
Long Ladders possible with:
Bonding and Encapsulation
Edge joint and wire bonds before
encapsulation
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
The Rise of Silicon Detectors
Cost /Area of Single-sided Silicon Strip Detectors
(double-sided factor 2.5 higher)
Trends in the Cost of
Silicon Detectors
Increased Area 4” -> 6”
Better utilisation of area
Improved Quality
e.g. GLAST detectors:
<2nA/ cm2
<2*10-4 bad channels
4"
6"
2
Cost /Area [ $/cm ]
Cost of processing wafers
reduced ~ 4x
100
Wafer Size
Mark 2
DC coupl.
GLAST ATLAS
"4"
ZEUS
DC coupl.
10
CDF
Nomad
(untested)
GLAST
6"
CMS
4"
Blank Wafer Price
6"
1
1985
1990
1995
2000
Year
(Guestimates by HFWS)
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
DC (Drift Chamber) vs. SSD (Silicon Strip Detector)
DC
Tasks
SSD
Excellent
Team
Excellent
Control E,
Gain
Electrostatic
Design
Silicon
Valley
Many
tricky parts
Manufacturing
Silicon
Valley,
Modular
Job
Shoppers
Assembly
Silicon
Valley
Discreets
Hybrids
Read out
ASICs
E, T, HV,
Gas,
Whiskers
Operations
Never
Calibrate
Low
Power
d-rays,
sparks
Performance
Fast,
Big S/N
What to do next?
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Typical Low Tech University Jobs
What to do next?
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Typical Low Tech University Jobs
What to do next?
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Tracking Milestones: Fixed Target
That’s how it all began
Silicon Detectors
~ 5cm x5cm
Fixed Target experiments with high rates:
Na11 (ACCMOR), Na14, E706. E691
Detect heavy decaying particles
through their finite decay distance
What to do next?
Fanout-Cables
Amplifiers
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Tracking Milestones: Vertex Detectors
The big step forward in Mark2:
ASIC’s (A. Litke et al)
Vertex Detector Paradigm
ASIC’s,
Few thin layers,
Close in.
Every LEP
Experiment has a
Vertex Detectors:
Double-Sided
AC-coupled
ALEPH {A. Litke et al)
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Tracking Detectors: CCD
300M pixel CCD device for SLD
(A. Seidem, T. Schalk, B. Schumm)
Few um resolution in two coordinates
Follow the (Industrial) Leader..
SLD
X
Primary
Z Vertex
Detached Vertexes
In B and anti-B
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Tracking Milestones: Speed and Rad.Hardness
LPS at HERA
(D. Dorfan, N. Spencer, J. DeWitt, N. Cartiglia, E.
Barberis, A. Seiden, D. Williams, HFWS )
“Fixed Target” at Collider
56 planes, 50k channels
Elliptical shapes!
2mm from 800GeV beam
Importance of Electronics:
rad hard
fast
low noise
low power
Hadron-Machines:
Radiation Damage
2 chip set:
Bipolar+CMOS
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Tracking Milestones: Highest Luminosity LHC
ATLAS: Silicon Tracker
(A. Seiden, D. Dorfan, A. Grillo, N. Spencer,
S.Kachiguin, F. Rosenbaumm, M. Wilder, HFWS)
Simple Detectors,Optimized Electronics
Thermal management
Temperature Range :
Vertex Detector  Inner Detector
Change in Paradigm:
coverage of large area
electronics inside tracker volume
-17oC (cooling pipe) to +16oC (ASICs)
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Tracking Milestones: Highest Luminosity LHC
Continued Paradigm Change:
>20 layers of Si, outside radius : ~1.1m
~1R.L. in tracking volume
almost exact size of old wire chambers!
Silicon has arrived:
all Silicon Inner Detector
Si Area 223m2,
-6” Wafers –
(Ariane Frey et al)
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Technology Transfer of Silicon Detectors
Protons
Biology
Small-scale
Large-scale
g-Rays
Space Science
C.Rays
X-rays
Medicine
Charged Particle
Tracking in HEP
Industrial Base
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Si Tracking in Space: Sileye
Cosmonaut Adveev on Mir
Sileye
Investigate light flashes
seen by Cosmo-/Astro-nauts during
Orbital flights.
Occurrence of flashes
well correlated with areas of
high flux of Cosmic ray particles.
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Photon Detection in Astronomy: Direction, Direction,..
Photon Attenuation Coefficient
Attenuation of Phtotons
N(x) = Noe- l x
l varies by 105!
OpticalX-rays
Need Focus:
Lenses
Mirrors
Collimators
Coded Masks
Proximity
Attenuation < 0.3%
coefficient Conversions
l= (7/9)/Xo in one SSD!
PairProduction
Direction
g
anticoincidence
shield
Compton
Partial
Direction
conversion
foil
particle tracking
detectors
e+
e–
calorimeter
(energy measurement)
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
GLAST: Pair Conversion Telescope
Gamma-rays convert into e+e- pairs,
are tracked and their energy measured
Gamma is reconstructed from e+e- tracks
g
charged particle
Reconstruct Vertex
anticoincidence
shield
conversio
n foils
particle
tracking
detectors
ee+
calorimeter
New Paradigm:Add material
(energy
measurement) into tracking volume:
Maximize
Converter Thickness t
Number of
Conversion Probability ~ t
Converters
Pointing RMS ~ t
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
GLAST Gamma-Ray Large Area Space Telescope
An Astro-Particle Physics Partnership Exploring the High-Energy Universe
Design Optimized for Key Science Objectives
• Understand particle acceleration in AGN, Pulsars, & SNRs
• Resolve the g-ray sky: unidentified sources & diffuse emission
• Determine the high-energy behavior of GRBs & Transients
Proven technologies and 7 years of design,
development and demonstration efforts
• Precision Si-strip Tracker (TKR)
• Hodoscopic CsI Calorimeter (CAL)
• Segmented Anticoincidence Detector (ACD)
• Advantages of modular design
• NASA, DoE, DoD, INFN/ASI, Japan, CEA, IN2P3, Sweden
Challenges of Science in Space
• Launch
• Limited Resources
• Space Environment
Resolving the g-ray sky
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
GLAST Large Area Telescope (LAT)
Tracker
• Array of 16 identical
“Tower” Modules, each
with a tracker (Si
strips SSD)
10,000 SSD
83m2 area
~1M channels,
~ 5M wire bonds
Grid
DAQ
Electronics
ACD
Calorimeter
Thermal
Blanket
• A calorimeter (CsI
with PIN diode
readout) and DAQ
module.
• Surrounded by finely
segmented ACD
(plastic scintillator
with PMT readout).
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
SCIPP
GLAST Silicon Tracker
Tower Structure (walls, fasteners)
Engineering: SLAC, Hytec
Procurement: SLAC
I
SSD Procurement, Testing
Japan, Italy, SLAC
I
(R. Johnson, W. Atwood, W.
Rowe, A. Webster, N. Spencer, S. Kachiguine,
W. Kroeger, M. Hirayama, M. Sugizaki, B.
Baughman, HFWS)
SSD Ladder
Assembly
10,368
Tower Assembly
and Test
SLAC (2)
Italy (16)
2592
Tray Assembly
and Test
Italy
18
UCSC
I
342
I
Most Production
and Assembly Steps Testing: Academic &
done in Industry = I Research Institutions
I
342
Electronics Design,
Fabrication & Test
UCSC, SLAC
Cable Plant
I
Italy
648
Composite Panel & Converters
Engineering: SLAC, Hytec, and Italy
Procurement: Italy
I
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Typical High Tech University Jobs
4 trays, 10 eyes & 10 hands
2 trays and 2 observers
2 delicate hands
17 trays!
All done and all smiles.
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Application of Silicon Detectors: No Limits
We build instruments to explore
the structure of our world
from Quarks (<10-20m)
to the entire Universe (>1028m).
Astrophysics:
Imaging, Tracking
Medicine:
Imaging
X-talography:
Imaging
Nuclear Physics
X-Spectroscopy
Particle Physics:
Tracking
Silicon Detectors are used
for experimentation
at every scale.
Gravitation
Electro-magnetic
Weak Strong
The largest SSD systems
are in Astro- and Particle
Physics.
We trying to play catch-up
in Life Sciences.
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
TKR Interconnects: Industry Job
~ 1,000,000 TKR Channels
~ 6,000,000 encapsulated Wire Bonds
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
GLAST Front-End Electronics ASIC
Binary Readout:
•Low-power (~200uW/channel)
•Peaking time ˜ 1.3 ms
•Low noise (Noise occupancy <10-5)
•Threshold set in every ASIC
•Separate Masks for Trigger and
Readout in every Channel
•Trigger = OR of one Si plane
(1536 channels)
Pulse Height:
Time –over-Threshold on the OR of
Si plane
Distinguish single tracks
from two tracks
in one strip
Electron Events
every
Photon Events
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Prototyping of the GLAST SSD
The SSD design has been finalized and
procurement is underway
11,500 SSD inlude 10% Spares
Qualify Prototypes from HPK
(experience with ~5% of GLAST needs)
0.1*specs
+340
Additional Prototypes: Micron (UK), STM (Italy), CSEM (Switzerland)
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Radiobiology
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Some Basic Questions in Radiobiology:
• It’s the DNA, stupid!
• Are there different classes of damage depending on the Linear Energy
Transfer (LET) and number of ionizations/DNA molecule?
LET
# of Ionizations
Damage
Low
1-5
Repairable ?
High
6-12
Irreparable ?
Very High
>12
Recombination &
Saturation ?
• By-stander effect: Damage is being transmitted to distant cells
• Effect of OH- radicals in the damage process
• Improve dosimetry of proton beam for cancer therapy
Collaboration (NASA-CalSpace)
Loma Linda U. & UCSC (SCIPP & CfO)
(A. Seiden, R. Johnson, W. Kroeger, P. Spradlin, B. Keeney,
HFWS)
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Radiation Damage DNA
Ionization event (formation of water
radicals)
Light damage- reparable
Primary particle track
delta rays
eOH•
Water radicals attack the
DNA
Clustered damage- irreparable
The mean diffusion distance of OH radicals before they react is only 2-3 nm
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Project Goals
• Establishment of a nanodosimetric gas model to
simulate ionizations in DNA and associated water
• Plasmid-based DNA model to measure DNA damage
• Develop models to correlate nanodosimetry with
DNA damage
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Principle of Nanodosimetry (Statistical Approach)
1nm
solid
1 mm @ .001 atm (~1 torr)
1 um @ 1 atm
X 1000
X 1000
DNA
Propane
gas
Low pressure propane gas
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Schematic of Nanodosimeter
particle
low pressure
gas
d electron
ion
vacuum
ion counter
E2
(strong)
E1
differential pumping
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Setup and Silicon Modules
Localization of Protons
2 Silicon Strip Detector
(SSD) Modules
ND Vessel
VME CRATE
SSD DAQ
PC W/ DAQ
PCI Card
Ion counter
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
ND Ion Cluster Spectra
Event with 6 ions
0
-5
-20
0
1
2
microseconds
3
A primary particle event is followed by an ion trail
registered by the ion counter (electron multiplier)
For low-LET irradiation, most events are empty
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
ND Ion Cluster Spectra
Ion Cluster Spectra
Ion cluster spectra depend on particle type and
energy as well as position of the primary particle
track
The average cluster size increases with increasing
LET
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Proton Energy Measurement
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Connection Nanodosimetry - Radiobiology
Relative frequency
Radiation
Ionization
Cluster Spectra
Nanodosimeter
%90
%88
%86
%16
%14
%12
%10
%8
%6
%4
%2
%0
protons 4 MeV
 5 MeV
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Cluster size
ssb
dsb
intact
mobility
0 minutes
15 minutes
30 minutes
60 minutes
120 minutes
Plasmid Sample
Gel
Electrophoresis
Incubation with
Base Excision
Enzymes
Frequency of
lesions of different
complexities
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Radiobiological Model
• Plasmid (pHAZE)
– Irradiation of thin film
of plasmid DNA
in aqueous solution
– Three structural forms:
• superhelical (no damage)
• open circle (single strand break)
• linear (double strand break)
– Separation by agarose gel electrophoresis
– Fluorescent staining and dedicated imaging system
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
What is needed?
Global (Nanodosimetry):
Ionization
Cluster Spectra
Relative frequency
Radiation
Well in Hand ?
Nanodosimeter
%90
%88
%86
%16
%14
%12
%10
%8
%6
%4
%2
%0
protons 4 MeV
 5 MeV
Correlation needed!
Tag individual Interaction,
Investigate Damage
Frequency ofin detail on struck molecules
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Cluster size
ssb
dsb
intact
mobility
0 minutes
15 minutes
30 minutes
60 minutes
120 minutes
Plasmid Sample
lesions of different
complexities
Gel
Electrophoresis
Incubation with
Base Excision
Enzymes
Local: Needs Improvement
No Radiometry Measurement
Correlated with Damage on
individual DNA Molecule
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Particle Tracking Silicon Microscope (PTSM)
Protons produce damage AND identify damaged organism
Transfer to Automated
Microscope when
Occupancy ~ 10%
Worms in Liquid Phase
(directly on SSD)
Double-sided SSD:
x-y coordinate, Energy,
“Cluster characteristics”.
Assay with Automated
Microscope using
stored x-y coordinates
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Gametogenesis in the adult hermaphrodite of C. elegans
oocyte
eggs in uterus
spermatheca
vulva
gonad
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Chromosome structures in the gonad of the adult hermaphrodite
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
0-8h: II (early embryogenesis) + III (diakinesis oocyte)
8-24h: III + IV + V + VI (diplotene to pachytene nuclei)
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Medicine
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Application: Compton Camera in Medicine
Compton Camera:
Silicon detector measures the first scatter
Calorimeter measures the energy and direction
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Strip Detectors in Medicine: Mammography
Large objects, “proximity focussing”
Need large detectors!
Scan collimated X-ray Source
across Si strips
scan
X-ray
direction
source
Gammex RMI phantom
at 0.7 mGy MGD
precollimator
object
aft-collimator
Excized breast tissue
5 cm x 7 cm x 4 cm
at 0.3 mGy MGD
silicon strip detector
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Strip Detectors in Medicine: Mammography
Stationary “Telescope” of
Flat Synchrotron beam and Collimator and edge-on Si Detector
Scan Sample/Patient.
Edge-on Si strips
Have high efficiency
No Ghost problem
= “Pixels”
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Acknowledgements
• LLUMC
Vladimir Bashkirov
George Coutrakon
Pete Koss
• WIS
Amos Breskin
Rachel Chechik
Sergei Shchemelinin
Guy Garty
Itzik Orion
Bernd Grosswendt - PTB
• UCSD - Radiobiology
– John Ward
– Jamie Milligan
– Joe Aguilera
• UCSC - SCIPP
–
–
–
–
–
Abe Seiden
Hartmut Sadrozinsky
Brian Keeney
Wilko Kroeger
Patrick Spradlin
The nanodosimetry project has been funded by the National Medical Technology Testbed
(NMTB) and the US Army under the U.S. Department of the Army Medical Research
Acquisition Activity, Cooperative Agreement # DAMD17-97-2-7016. The views and
conclusions contained in this presentation are those of the presenter and do not necessarily
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
A Silicon Telescope For
Nanodosimetry
A collaboration between Loma Linda University Medical Center,
the Weizmann Institute of Science, UC San Diego, and
the Santa Cruz Institute for Particle Physics, UC Santa Cruz
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Collaborators
Loma Linda University Medical Center
Reinhard Shulte
Vladimir Bashkirov
George Coutrakon
Peter Koss
Weizmann Institute of Science
Amos Breskin
Rachel Chechik
Sergei Shchemelinin
Guy Garty
Itzhak Orion
University of California, San Diego
John F. Ward
Joe Aguilera
Jamie Milligan
Santa Cruz Institute for Particle Physics
(University Of California, Santa Cruz)
Abe Seiden
Hartmut Sadrozinski
Robert P Johnson
Wilko Kroeger
Patrick Spradlin
Brian Keeney
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Radiation Damage To DNA
Ionization event (formation of water
radicals)
Light damage- reparable
Primary particle track
delta rays
eOH•
Water radicals attack the
DNA
Clustered damage- irreparable
The mean diffusion distance of OH radicals before they react is only 2-3 nm
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Bethe-Bloch in ND
Linear Energy Transfer LET:
dE = f (bg ) [MeV/ g ]
dX
cm2
DE = dE DX , DX = D [ g ]
dX
cm2
~1/b1.5
measure p
MIP
Radiation damage in DNA occurs within 2-3nm

D( propane) =  DNA  D(DNA)
propane

D( propane@1mbar) =  STP  D( propane@ STP)
1mbar
D( propane@1mbar) =10001000 D(DNA)
1nm(DNA) =1mm( propane@1mbar)
Rad
UCSC Physics 205 2002
1nm
solid
1 m m @ 1 atm.
X 1000
DNA
Hartmut F.-W. Sadrozinski , SCIPP
1 mm @ .001 atm.
X 1000
Propane
gas
Low pressure propane gas
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
4 Silicon Detectors give position and LET, allow trigger on
any combination of planes
Eweak
electron
Incoming
Proton
Low Pressure
Gas
X-Y
Estrong
NOT TO
SCALE
Vacuum
Ion
Ion
Counter
Aperture
Y-X
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Setup and Silicon Modules
VME CRATE
Localization of Protons
2 Silicon Strip Detector
(SSD) Modules
SMD
Readout
PC W/ DAQ
PCI Card
Ion
Counter
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Time-Over-Threshold (TOT):
Digitization of Position and Energy with large Dynamic Range
TOT  charge  LET!
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Charge Sharing in SMD’s
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
TOT Spectra For Low-Energy ProtonsAn absolute calibration of SMD
UCSC Physics 205 2002
Results
Hartmut F.-W. Sadrozinski , SCIPP
Proton
energy
[MeV]
Mean TOT
[us]
RMS TOT
[us]
Charge
Deposition
400um Si
[fC]
TOT
expected by
Bethe-Bloch
[us]
13,500
7
1.4
5.3
6.5
250
12.3
2.6
13.5
13.7
39
53.4
6.4
54
55
27
70.4
7.5
67.5
69
24
78.3
8.5
76.5
78
22
84.4
9.8
81
82
17.6
105
11.5
99
101
9.5
108
15
189
105
7.4
109
21
243
105
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
TOT and Resolution Measured
TOT expected through Bethe-Bloch
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Proton Energy Measurement
E = E/TOT* TOT =
1/(TOT/ E)* TOT
10
10
Resolution of TOT System
EE
LET
Energy
1


1

0.1
0.1
TOT
Saturation
0.01
10
4
100
1000
10
Proton Energy [MeV]
0.01
UCSC Physics 205 2002
Hartmut F.-W. Sadrozinski , SCIPP
Conclusion
1. Silicon Detectors allow flexible triggering on primary particles.
2. Silicon Detectors yield fantastic spatial resolution—60 mm
3. We can Measure LET to 10-20% in each of 4 planes
Given LET, we know Energy to 20-25% in each plane
through Bethe-Bloch up to 250 MeV
Silicon detectors give Nanodosimetry position and energy,
making it possible to simulate ionization of DNA in a gas.