X,Sun
1
STAR Regional Meeting, Oct 23, 2010, SDU
STAR
STAR Heavy Flavor Tracker Upgrade
--
Status of
PXL
Detector
Xiangming
Sun(
孙向明
)
Lawrence Berkeley National Lab
L. Greiner,
H.
Matis
T.
Stezelberger
M.
Szelezniak
C. Vu
H.
Wieman
… …
X,Sun
2
STAR Regional Meeting, Oct 23, 2010, SDU
STAR
Outline
•
Heavy Flavor Tracker
upgrade
in STAR
at RHIC
•
Fast Simulation of Detector Performance
•
Monolithic Active Pixel Sensor
•
PXL Readout Electronics
•
Power Consumption and Cooling test
•
Summary
X,Sun
3
STAR Regional Meeting, Oct 23, 2010, SDU
STAR
STAR Detector at RHIC
RHIC (Relativistic heavy ion
collider)
Brookhaven National Lab
http://www.bnl.gov/rhic/
STAR(the
solenoidal
tracker at RHIC )
is one of Detector at RHIC.
It specializes in tracking the thousands
of particles produced by each ion
collision
X,Sun
4
STAR Regional Meeting, Oct 23, 2010, SDU
STAR
Physics Goals
heavy ion collision generate a very hot and
dense medium
Charm particle is proposed to probe medium
property
Direct Topological reconstruction of Charm
Detect charm decays with small c
Ⱐ
楮捬畤楮朠⁄
0
䬠
(122.9 m
m
)
Method: Resolve displaced vertices
(100
-
150
microns)
X,Sun
5
STAR Regional Meeting, Oct 23, 2010, SDU
STAR
Inner Detector Upgrades
TPC
–
Time Projection Chamber
(main tracking detector in STAR)
HFT
–
Heavy Flavor Tracker
SSD
–
Silicon Strip Detector
r = 22 cm
IST
–
Inner Silicon Tracker
r = 14 cm
PXL
–
Pixel Detector
r = 2.5, 8 cm
We track inward from the TPC with graded resolution:
TPC
SSD
IST
PXL
~1mm
~300µm
~250µm
vertex
<30µm
X,Sun
6
STAR Regional Meeting, Oct 23, 2010, SDU
STAR
PXL Detector
Ladder with 10
MAPS sensors
(~ 2
×
2 cm each)
M
A
P
S
R
D
O
b
u
f
f
e
r
s
/
d
r
i
v
e
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s
4
-
l
a
y
e
r
k
a
p
t
o
n
c
a
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e
w
i
t
h
a
l
u
m
i
n
i
u
m
t
r
a
c
e
s
2
layers: 2.5,8 cm
10
sectors
1+3
ladders
/ sector
Mechanical support with
kinematic mounts
X,Sun
7
STAR Regional Meeting, Oct 23, 2010, SDU
STAR
Some PXL Parameters
Layers
Layer 1 at 2.5 cm radius
Layer 2 at 8 cm radius
Pixel patch size
18.4
m
m X
18.4
m
m
Hit resolution
10
m
m
rms
Position stability
6
m
m
rms
(20
m
m envelope)
Radiation thickness per
layer
X/X0 = 0.37%
Integration time
(affects pileup)
200
m
s
Number of pixels
0.2 ms
436 M
Radiation tolerance
300
kRad
Rapid detector
replacement
< 8 Hours
critical
and
difficult
more than a factor of 2 better than other vertex detectors
(ATLAS, ALICE and PHENIX)
X,Sun
8
STAR Regional Meeting, Oct 23, 2010, SDU
STAR
Fast Simulation of Detector Performance
detector layer 1
detector layer 2
r
2
r
1
true vertex
perceived
vertex
x
x
v
Position resolution:
1, Effective pixel Size :
2, Multiple Coulomb Scattering
Line assumption:
using line created by two points in
two layers to calculate dispersion
from true vertex.
Consistent with full
Geant
simulation
Free parameters :
Pixel resolution
Detector thickness
X,Sun
9
STAR Regional Meeting, Oct 23, 2010, SDU
STAR
Position Resolution
vs
Significance
Significance=
signal
(
signal+background
)
1/2
______________
Effective pixel size=21.5um
It includes:
pixel patch size 18.4um
thermal distortion 4.5um
cooling vibration 10um
D0 momentum=1GeV/c
X,Sun
10
STAR Regional Meeting, Oct 23, 2010, SDU
STAR
Detector Thickness
vs
Significance
X/X0=0.58%
It includes:
first layer thickness
0.37%
beam pipe thickness
0.21%
(Beryllium)
D0 momentum=1GeV/c
X,Sun
11
STAR Regional Meeting, Oct 23, 2010, SDU
STAR
Association
Rate
vs
Pointing Resolution and Hit Density
Nhits
per sensor=250 for 200us integration time
Pointing resolution=250um
Association
rate=
80
%
Association rate: associating hits to tracks from outer detector
X,Sun
12
STAR Regional Meeting, Oct 23, 2010, SDU
STAR
Monolithic Active Pixel Sensors
•
IPHC
-
DRS (former IRES/LEPSI) proposed using MAPS for high energy physics in
1999
•
Standard
commercial CMOS technology
•
Sensor
and signal processing are integrated in the same
silicon
wafer
•
Proven thinning to
50
micron
•
Signal is created in the low
-
doped epitaxial layer (typically ~
10
-
15
μm
) → MIP
•
signal is limited to <
1000
electrons
•
Charge
collection is mainly through thermal diffusion (~
100
ns), reflective
boundaries at
p
-
epi
and
substrate → cluster size is about ~
10
pixels (
20
-
30
μm
pitch)
•
Room temperature operation
MAPS pixel cross
-
section (not to scale)
X,Sun
13
STAR Regional Meeting, Oct 23, 2010, SDU
STAR
From Analog to Binary Readout
V
R
E
F
1
P
W
R
_
O
N
M
O
S
C
A
P
R
E
S
E
T
V
R
E
F
2
V
D
D
P
W
R
_
O
N
V
R
1
V
R
2
R
E
A
D
C
A
L
I
B
I
S
F
P
I
X
E
L
C
O
L
U
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N
C
I
R
C
U
I
T
R
Y
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F
F
S
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T
C
O
M
P
E
N
S
A
T
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D
C
O
M
P
A
R
A
T
O
R
(
C
O
L
U
M
N
L
E
V
E
L
C
D
S
)
S
O
U
R
C
E
F
O
L
L
O
W
E
R
l
a
t
c
h
Q
Q
_
R
E
A
D
R
E
A
D
+
+
+
+
+
+
-
-
-
-
L
A
T
C
H
C
A
L
I
B
R
E
A
D
Digital readout
–
offers increased speed but requires on
-
chip discriminators
or ADCs and increased S/N for on
-
chip signal processing
Analog readout
–
simpler architecture
but slower readout
X,Sun
14
STAR Regional Meeting, Oct 23, 2010, SDU
STAR
MAPS Integration Time = Readout Time
•
Typical sensor readout
–
“rolling shutter” mode.
–
Integration
time = array readout
time
•
Column parallel readout architecture
–
All columns readout in parallel and
then multiplexed to one output
–
Integration
time = column readout
time
–
Integration time =
200
us
X,Sun
15
STAR Regional Meeting, Oct 23, 2010, SDU
STAR
PXL Readout Electronics
2 m (42 AWG TP)
6
m (
24
AWG TP)
100 m (fiber optic)
4 ladders per sector
1 Mass Termination Board (MTB) per sector
1 sector per RDO board
10 RDO boards in the
PXL
system
RDO motherboard + Xilinx Virtex
-
5 Dev Board
RDO PC with DDL link to RDO board
Mass termination board + latch up
protected power daughtercard
← Front Back ↓
X,Sun
16
STAR Regional Meeting, Oct 23, 2010, SDU
STAR
RDO System Design
–
Physical Layout
1
-
2 m
Low mass twisted pair
6
m
-
twisted pair
Sensors / Ladders / Sectors
(interaction point)
LU Protected Regulators,
Mass cable termination
RDO Boards
DAQ PCs
(Low
Rad
Area)
DAQ Room
Power
Supplies
Platform
30 m
100 m
-
Fiber optic
30
m USB
Control
PCs
30
m
400MB/s
X,Sun
17
STAR Regional Meeting, Oct 23, 2010, SDU
STAR
Firmware Structure
17
DDL/USB
PC
sensor
Xilinx Virtex
-
5 Dev Board
X,Sun
18
STAR Regional Meeting, Oct 23, 2010, SDU
STAR
I
O
D
elay for
D
igital
D
ata
A
lignment
800 channels, 160 MHz digital
signals pass
8 meters
and 3 buffering stages before
arriving FPGA
.
digital need to be aligned in FPGA end.
Solution: FPGA
iodelay
function
Status
•
Data Path Architecture Validated
•
Measured BER (bit error rate) of < 10
-
14
X,Sun
19
STAR Regional Meeting, Oct
23
,
2010
, SDU
STAR
System Control
C
ommand
generator:
command.exe
Hex file
usb.exe
download_data_block_to_F
EE
0x0402fffd
0x1d82ff3f
0x1502ffcf
0x2642ffff
0x2642fdff
0x2202feff
0x0c03fff0
0x1547ffff
0x1547ffff
0x1547ffff
0x1547ffdf
0x0cc7ffff
0x0cc7ffff
………….
DAQ
PC
rorc_receive
getda
ta
Control
PC
X,Sun
20
STAR Regional Meeting, Oct 23, 2010, SDU
STAR
Power Consumption and Cooling Test Setup
•
Sensor: 170
mW
/cm
2
→ 270 W for PXL sensors
•
2 W/drivers/cable
→ 80 W for PXL drivers
Silicon heater put on ladder
X,Sun
21
STAR Regional Meeting, Oct 23, 2010, SDU
STAR
Cooling
Tests
at ~360 W
–
IR
Images
Air 13.8 m/s
Hot spots ~37
°
C
Air 10.1 m/s
Hot spots ~41
°
C
Air
4.7
m/s
Hot spots ~
48
°
C
Air temperature ~27
°
C
From infra
-
red camera
X,Sun
22
STAR Regional Meeting, Oct
23
,
2010
, SDU
STAR
0
2
4
6
8
10
12
14
16
18
0
5
10
15
20
25
30
location on ladder (cm)
vibraitons RMS (um)
~4.7 m/s
~9.3 m/s
~12.8 m/s
~4.7 m/s (fixed end)
~9.3 m/s (fixed end)
~12.8 m/s (fixed end)
Vibrations
Caused
by
Airflow
Beginning of the driver
section
(Supported end)
End of sensor
section
(Unsupported end)
Using capacitance sensor to measure
vibration
X,Sun
23
STAR Regional Meeting, Oct 23, 2010, SDU
STAR
Ionizing Radiation Tolerance
MIMOSA
-
22 Testing in 10
KeV
X
-
Rays in Lab
MIMOSA
-
22ter
Signal/noise ratio >=20 after 300
kRad
Ionizing radiation (300
e+e
-
pairs)
Non
-
ionizing radiation is under investigation
X,Sun
24
STAR Regional Meeting, Oct
23
,
2010
, SDU
STAR
•
We have a well advanced mechanical design that is in the
process of being verified by simulation and prototyping.
•
The prototype RDO system is performing well.
•
Sensor development with IPHC is on schedule and we
expect the first prototype final sensor delivery in
2011
.
•
The ladder cable development is on schedule and we are
evaluating the ITB performance with the full compliment of
10
working sensors.
Summary
Our current status:
The PXL is expected to be
fully installed in 2013 for RHIC Run14
X,Sun
25
STAR Regional Meeting, Oct 23, 2010, SDU
STAR
X,Sun
26
STAR Regional Meeting, Oct
23
,
2010
, SDU
STAR
X,Sun
27
STAR Regional Meeting, Oct 23, 2010, SDU
STAR
X,Sun
28
STAR Regional Meeting, Oct
23
,
2010
, SDU
STAR
Summary
Effective pixel size 21.5 um
Layer thickness X/X0=0.37%
Air speed 10.1m/s
Sensor max temperature 41
°
C
Vibration xx um(included in
Effective pixel size
)
The integration time 200 us
Hit density during
integration 250
Association rate 80%
Readout Electronics
match the requirement
Our current status:
The PXL is expected to be
fully installed in 2013 for RHIC Run14
Please give status
X,Sun
29
STAR Regional Meeting, Oct 23, 2010, SDU
STAR
X,Sun
30
STAR Regional Meeting, Oct
23
,
2010
, SDU
STAR
PXL Detector
Ladder with 10
MAPS sensors
(~ 2
×
2 cm each)
M
A
P
S
R
D
O
b
u
f
f
e
r
s
/
d
r
i
v
e
r
s
4
-
l
a
y
e
r
k
a
p
t
o
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c
a
b
l
e
w
i
t
h
a
l
u
m
i
n
i
u
m
t
r
a
c
e
s
Mechanical support with kinematic
mounts
Cabling and cooling
infrastructure
New beryllium beam pipe
(
800
µ
m thick, r =
2.5
cm)
2 layers
10
sectors
3+1
ladders
/ sector
X,Sun
31
STAR Regional Meeting, Oct 23, 2010, SDU
STAR
Direct measurement has not been done so far.
Based on estimates (http://rnc.lbl.gov/~wieman/radiation dose
straus
oct
2007 HW.ppt) and TLD projection.
•
For the radius of 2.5 cm:
–
Ionizing radiation:
•
Total dose: 155
kRad
•
TLD projection: 300
kRad
–
Non
-
ionizing radiation
•
average
pion
count for 1 Yr: 3x1012 cm
-
2
•
TLD projection (
pion
assumption): 12x1012 cm
-
2
Radiation Environment
X,Sun
32
STAR Regional Meeting, Oct
23
,
2010
, SDU
STAR
Ionizing Radiation Tolerance
MIMOSA
-
22 Testing in 10
KeV
X
-
Rays in Lab
MIMOSA
-
22ter
Signal/noise ratio >=20 after 300
kRad
Ionizing radiation (300
e+e
-
pairs)
Non
-
ionizing radiation is under investigation
X,Sun
33
STAR Regional Meeting, Oct 23, 2010, SDU
STAR
•
The Heavy Flavor Tracker (HFT) is an upgrade project for the STAR
detector at RHIC, It will allow the topological reconstructions of the heavy
flavor hadrons via their
hadronic
decays . The HFT consists of three coaxial
detectors: SSD(Silicon Strip Detector), IST(Intermediate Si
-
Tracker)
and
PXL(a pixel detector). The PXL is the inner
-
most and highest precision
detector in HFT. The sensor chip we use to build PXL is developed in
Monolithic Active Pixel Sensor(MAPS) technology. Each sensor has
1024X1188 pixels with 18.4 micron pitch and 50 micron thickness. The
integration time is 200 us. Correlated double sampling (CDS) and
digitization are performed on the sensor chip. The readout electronics is
designed to handle 400 sensors which are grouped in 10 sectors. In this
talk, we discuss the relation between the physics goals and sensor
characteristics, such as pixel size, sensor thickness, integration time,
radiation tolerance and power consumption. We introduce the on
-
chip
electronics design to perform CDS and digitization. We also show the
readout electronics designed to handle R&D tests and physics data
acquisition. The PXL is expected to be
fully installed in 2014 for RHIC
Run14
X,Sun
34
STAR Regional Meeting, Oct 23, 2010, SDU
STAR
Initial testing with ~75
μ
m
travel past touchdown
30
μ
m additional
lowering of probe pins
Phase
-
1 discriminator transfer
functions ƒ(threshold voltage)
observed on two of the probed
sensors :
Sensors designed with dedicated probe pads in the sensor pad ring.
13 full
-
thickness, diced sensors probe tested.
Up to 3 probe tests on a sensor.
We will begin testing thinned sensors within the next few days
Status
•
Automated and scripted system
for sensor testing is in place.
•
Vacuum chuck for handling up to
twenty 50
μm
thick sensors is
being tested
•
Ongoing sensor testing
Probe Tests
X,Sun
35
STAR Regional Meeting, Oct
23
,
2010
, SDU
STAR
Cooling tests at ~360 W
•
Initially: 100 mW/cm
2
→ 160 W for PXL sensors
•
Updated: x1.7
→ 270 W for PXL sensor
•
2 W/drivers/cable
→ 80 W for PXL drivers
Ladder
section
Measured
resistance
(Ω)
Current
(A)
Voltge
(V)
Power
(I∙V)
(W)
sensors
Sector 1
(Pt heaters)
6.6
2.06
6.97 + 7.96
30.7
Sectors 2
-
10
4.6 || 3.7
10.6
23.1
244.8
drivers
Sectors 1
-
5
1.4
5.3
8.23
43.6
Sectors 6
-
10
1.4
5.3
8.03
42.5
Total
Power
~361
X,Sun
36
STAR Regional Meeting, Oct 23, 2010, SDU
STAR
MAPS @ Institut Pluridisciplinaire Hubert Curien
•
IPHC
-
DRS (former IRES/LEPSI) proposed using MAPS for high energy
physics in 1999
•
CMOS & ILC group today
–
6
physists
–
9 microcircuit designers
–
6 test engineers
–
7 PhD students
CNRS
-
IPHC, Strasbourg
-
Cronenbourg
More than 30 prototypes developed
–
several pixel sizes and architectures (simple
3
-
transistor cells, pixels with in
-
pixel amplifiers
and CDS processing)
–
different readout strategies (sensors operated
in current and voltage mode, analog and
digital output)
–
Large variety of prototype sizes (from several
hundreds of pixels up to 1M pixel prototype
with full
-
reticule size)
MIMOSA (Minimum Ionizing particle MOS Active sensor)
X,Sun
37
STAR Regional Meeting, Oct 23, 2010, SDU
STAR
PXL Hardware Architecture
8
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RDO motherboard
Mass Termination Board
Ladder
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