The new Silicon detector at RunIIb
Silicon Sensors in High Luminosity
environment
Layer
Layer
Layer
Layer
Layer
Layer
0:
1:
2:
3:
4:
5:
12 fold Axial
6 fold Axial-Axial
6 fold Axial-SAS(1.2)
12 fold SAS(1.2)-Axial
16 fold SAS(1.2)-Axial
20 fold Axial-Axial
The average material for the
RunIIa and RunIIb silicon
detector designs is compared
for
normal
incidence
trajectories as a function of
position along beam line
Less material than in RunIIa
due
to
compact
stave
structure and progress in
hybrid technology
Improvements Stave design
 extension of the
“contained b-jets” region
 more uniform radial
distribution
L1-L5: 180 staves can be produced
with the same mechanical fixture
(SVXIIa has 180 ladders, 5 sizes and
36 of each size)
1 bus cable, 6 sensors, 3 hybrids, 4 chips on
each hybrid (2 chip for beam pipe layer)
L0 is similar to RunIIa L00: axial
sensor at small radius, small strip
pitch and with very low mass
Parts
Improvements
 layout easy to mass produce
SVXIIa
Hybrids
Sensors
Ladders
SVXIIb
10
5
5
1
2
1
 L0 will guarantee a good impact parameter resolution for
unshared hits
 L1 strengthens the pattern recognition near the beam pipe
(redundancy of the axial layers ensures a good axial hit)
 L5 strengthens the connection to the COT
 Loss in z-resolution but better hits-tracks association
Configuration
As a result the sensors are subjected to:
 increase in leakage current and thus in shot noise, heat,..
 substrate-type inversion which affect the depletion voltage
R (cm)
Calcul. Dose RunIIb
*1013
(1 MeV eq-n cm-2 )
2.1
3.5
5.9
9.1
11.9
14.7
13.6
5.7
2.3
1.1
0.7
0.5
Layer
0
1
2
3
4
5
All 2300 sensors are <100> n-type singlesided high resistivity bulk silicon microstrip
detectors:
 operating at high voltages ( 350V), they
are radiation hard
 all SVXIIb detectors have intermediate
strips yielding excellent resolution
More sensors are required to maintain the
same tracking capability (SVXIIa had doubleside sensors that decrease the number of
detectors used)
 Silicon is actively cooled down (L0&L1-5C)
to decrease the leakage current
A stave, the RunIIA ladder, is a
structural element with 6 axial
sensors on one side and 6 axial or
small angle stereo sensors on the
other side. The two sides are
separated by a few mm.
The key feature of the RunIIb design
is the uniform stave design for 90%
of the sensors
Schematic of a stave:
Silicon detectors are damaged by radiation primarily through
displacement of Silicon or impurities from the lattice.
All layers
sd (mm)
Asymptotic
6
sd (mm)
Pt=2GeV
25
NO L1
NO L0
NO L0 or L1
7.5
9
15
27
51
79
Impact parameter resolution in r-f
for all axial sensors
Configuration
L2-L5 + 1 ISL
sz (mm)
Asymptotic
1.4
sz (mm)
Pt=2GeV
1.4
L2-L4 + 1 ISL
L2-L5 only
L2-L4 only
1.8
1.4
2.0
1.8
1.4
2.0
Impact parameter resolution in r-z
for all stereo sensors
Prototype sensors
Detectors are manufactured by
Hamamatsu
Photonics:
all
unirradiated prototyped sensors have
been FULLY CHARACTERIZATED at
Tsukuba, Purdue and UNM:
Irradiation
damage Study:
Neutron Irradiation
performed at UC Davis:
7*1013
1MeV eq-n
cm-2
&
1.4*1014 1MeV eq-n cm-2
SVX4 chip
After Irradiation Leakage Current vs Bias Voltage
environmental chamber T = - 25C
After irradiation Interstrip Capacitance vs Bias
Voltage
T=14C f=1MHz & AC signal = 5V
1.0E-02
7.0E-12
Interstrip capacitance (F)
The new detector SVXIIB has 6
layers with 2 barrels in z, each 66cm
long. As in RunIIa, the staves within
a layer are arranged in a castellated
patter. The RunIIa portcards have
been removed from the tracking
volume to minimize the mass
Leakage Current (A)
The new silicon detector
Layout
1.0E-03
1.0E-04
Sensor 60 T = - 25C
Sensor 60 expected @T= - 5 C
Sensor 60 T = 20C
6.5E-12
sensor 63 U250
6.0E-12
sensor 63 D120
sensor 60 U256
After Irradiation
Depletion Voltage
sensor 63 V = 130V
sensor 60 V = 128V
5.5E-12
5.0E-12
4.5E-12
Before Irradiation
sensor 63 Cint = 3.17 +/- 0.01 pF
sensor 60 Cint = 3.46 +/- 0.17 pF
4.0E-12
After Irradiation
sensor 63 3.3 pF
sensor 60 3.4 pF
3.5E-12
3.0E-12
0
1.0E-05
0
100
200
300
400
500
600
700
800
900
100
200
300
1000
400
500
600
700
800
900
Bias Voltage
For high fluence, good S/N ratio
thanks to:
Single strip leakage current
Ileak 95nA at T -5C
 Interstrip capacitance  3pF
128-channel device; 8-bit digitization on chip, deadtime
less, dynamical pedestal substraction,low power
SVX4 is 0.25 mm CMOS translation of SVX3D chip. Chips have been
irradiated to 16Mrad with Co-60 facility and no change has been observed:
enhanced radiation tolerance.
The data plot is from the 1st module where the bonding for each
chips was different: not bonded to anything, bonded to pitch
adapter,bonded to PA and one sensor, bonded to PA and 2 sensors.
As the capacitance increases you can see that the noise level
increases as expected: signal/noise 30% better than SVX3
10 modules fully assembled: hybrids work well
2 Electrical staves ALREADY build
The new SVXIIb will be installed in 2006
SENSORS
The plots show the b-tagging efficiency vs b-jet (studies performed
using RunIIa simulation) and the Higgs mass sensitivity as a function
of b-tag efficiency e (e is relative to 65%)
1000
Bias Voltage (V)
(6 months shutdown)
Svx4 chip