STATUS OF THE ROMAN POT MODULE DESIGN B' Perea Solano, CERN RD39 Collaboration, Geneva 35 December 2

1
CRYOGENIC SILICON MICROSTRIP DETECTOR MODULES FOR
UPGRADED LHC Ph.D. Thesis ? B. Perea Solano ?
CERN EP Seminar, 29th Nov 04 Dr. T. O.
Niinikoski - CERN ? Dr. F. Calviño Tavares - UPC

? FRAMEWORK and MOTIVATION ? THERMOELASTIC
DESIGN ? ALIGNMENT ? COOLING AND THERMAL TESTS ?
PROTOTYPE ASSEMBLY ? TESTS OF ELECTRONICS AT LOW
T ? CONCLUSIONS AND OUTLOOK
2
? FRAMEWORK ? MOTIVATION ? Cryogenic Silicon
Microstrip Detector Modules for Upgraded LHC.
CERN PH Seminar. 29th Nov. 04
1015
1014

• CERN - Large Hadron Collider (LHC) - Collisions
  of 7 TeV p at 4 points
• Silicon microstrip and pixel detectors used in
  the inner trackers
• At the design luminosity ? 1034 cm-2s-1 ? doses
  200 kGy at 10 cm in 10 years LHC
• Deterioration of silicon tracker performance
  (increase Vfd, I, decrease ?)
• State-of-art detectors are insufficient for
  long-term operation in the central parts of the
  LHC trackers, in particular after the luminosity
  upgrade to 1035 cm-2s-1

3
? FRAMEWORK ? MOTIVATION ? Cryogenic Silicon
Microstrip Detector Modules for Upgraded LHC.
CERN PH Seminar. 29th Nov. 04

• RD39 studies new detector techniques for trackers
  that meet the requirements of LHC after its
  upgrade Operation of detectors at cryogenic
  temperatures and current injected sensors
• 10 times higher radiation tolerance
• low Vfd
• increase of the ?
• suppression of leakage current
• faster detector and electronics
• extension of the sensitive area of the sensor to
  its physical edge edgeless

Inner Trackers after luminosity upgrade Very
forward elastic scattering measurement
CMS/TOTEM and ATLAS
TOTEM Total Cross Section, Elastic Scattering
and Diffraction Dissociation at the LHC. Roman
Pot stations located on each side of the
interaction point
4
? EDGE SENSITIVITY OF EDGELESS SILICON PAD
DETECTORS ? Cryogenic Silicon Microstrip
Detector Modules for Upgraded LHC. CERN PH
Seminar. 29th Nov. 04
Edgeless silicon pad detectors
80 cm
Diodes
CMS Tracker
Insensitive width 12.5 ? 8stat. ? 6sys. ?m
There is no evidence of an insensitive width
within the experimental error
B. Perea, Silicon Microstrip Detector Modules for
LHC, CERN Ph.D. Thesis, Universitat Politècnica
de Catalunya (UPC), ISBN 84-688-8952-0. B. Perea
et al., Edgeless silicon pad detectors, XIII
International Workshop on Vertex detectors,
Menaggio, September 2004. B. Perea et al., Edge
sensitivity of edgeless silicon pad detectors
measured with a high energy beam , to be
submitted to NIM.
5
? THERMOELASTIC DESIGN OF A CRYOGENIC MODULE ?
Cryogenic Silicon Microstrip Detector Modules
for Upgraded LHC. CERN PH Seminar. 29th Nov. 04

• Main requirements for LHC experiments
• Radiation hardness
• Low mass (multiple scattering)

Cryogenic operation of these modules would lead
to the camber of the sensors, peeling of Kapton
and fracture of fragile components (Si sensor)
ATLAS / CMS modules
6
? THERMOELASTIC DESIGN OF A CRYOGENIC MODULE ?
Cryogenic Silicon Microstrip Detector Modules
for Upgraded LHC. CERN PH Seminar. 29th Nov. 04

• Main requirements for LHC experiments
• Radiation hardness
• Low mass (multiple scattering)
• Minimize thermal stress in the structure during
  cool down and achieve flat T profiles in the
  module
• The material choice is guided by the thermal
  conductivity and dilatation of the silicon sensor
  and readout chips
• AlN, alumina and silica glasses could be used as
  insulating materials
• Silicon is used as a structural material for the
  support plate and pitch adapter

7
? THERMOELASTIC DESIGN OF A CRYOGENIC MODULE ?
Cryogenic Silicon Microstrip Detector Modules
for Upgraded LHC. CERN PH Seminar. 29th Nov. 04

• Evaporative cooling
• Two-phase flow Argon (high HTC, low ?p, low m)
• Argon at ps15 bar / Ts124 K
• Microtube directly integrated under PA, close
  to the heat sources
• CFC structure to absorb thermal dilatation of
  0.6 OD CuNi pipe
• Thermal separation between the heat source and
  the sensor
• CMS readout electronics ? APV25 ?
• Alignment holes and slots directly machined on
  the CFC spacer

8
? THERMOELASTIC DESIGN OF A CRYOGENIC MODULE ?
SIMULATIONS Cryogenic Silicon Microstrip Detector
Modules for Upgraded LHC. CERN PH Seminar. 29th
Nov. 04

• Thermal simulations performed with different
  materials and cooling configurations
• HEAT LOADS
• No heat load due to the sensor leakage current
  !
• APV25 readout chips ? 2.31 mW / channel ? 3 W
  full module (10 APV25)
• Thermal radiation load ? Two diffuse-gray
  surfaces forming a cylindrical or spherical
  enclosure
• Silicon Module (?10.19 ? A138 cm2 ) at 130 K
• Aluminium Pot (?20.06 ? A2345 cm2) at 300 K
• CAPILLARY PIPE ? Bulk T fluid 120 K ? Heat
  transfer coefficient 104 W/m2K

230 mW
9
? THERMOELASTIC DESIGN OF A CRYOGENIC MODULE ?
SIMULATIONS Cryogenic Silicon Microstrip Detector
Modules for Upgraded LHC. CERN PH Seminar. 29th
Nov. 04

• Thermal simulations performed with different
  materials and cooling configurations

2 cooling pipes 1 cooling pipe AlN
Support Silicon Module Support Plate Silicon Sili
con AlN Silicon Pitch adapter Pyrex Pyrex Py
rex Silicon Hybrid Alumina Alumina Alumina S
ilicon Epoxy Stycast 2850 Stycast
2850 Stycast 2850 Stycast 2850 TAr 110 K 120
K 120 K 120 K HTC 104 W/m2K 104 W/m2K 104
W/m2K 104 W/m2K Max. ?T 6 K 10 K 19 K 8.5 K
?Tmax 19 K
?Tmax 8.5 K
Silicon PA ? Al2O3 Hybrid ? Silicon
Pyrex PA ? Al2O3 Hybrid ? AlN support
10
? THERMOELASTIC DESIGN OF A CRYOGENIC MODULE ?
Cryogenic Silicon Microstrip Detector Modules
for Upgraded LHC. CERN PH Seminar. 29th Nov. 04
Module with a large sensor
The thickness of such a module is 1.107 of the
radiation length The single-sided baseline ATLAS
module is 45 thicker

• In a future design the full module could be made
  out of a single Si wafer !
• Hybrids processed using thick-film techniques in
  Silicon
• Integration of the cooling into microchannels
  directly machined on the support plate
• PA directly printed on the hybrid
• Alignment benefits

11
? THERMOELASTIC DESIGN OF A CRYOGENIC MODULE ?
FILLED EPOXIES Cryogenic Silicon Microstrip
Detector Modules for Upgraded LHC. CERN PH
Seminar. 29th Nov. 04
Measurement of the thermoelastic properties of
fused quartz filled radiation hard epoxies

• The thermoelastic properties of the adhesive and
  layer thickness are key parameters in the design
  of a cryogenic module
• Thermal dilatation mismatch between silicon and
  epoxies induces high stress in the structure
  during cool down
• Theoretical models predict lower thermal
  dilatation coefficient and higher E for epoxies
  filled with fused quartz (2 ?m)
• Lack of data available in literature

Measure the thermoelastic properties of Araldite
2011, Stycast 1266 and RG Type L, radiation
hard epoxies as a function of temperature
12
? THERMOELASTIC DESIGN OF A CRYOGENIC MODULE ?
FILLED EPOXIES Cryogenic Silicon Microstrip
Detector Modules for Upgraded LHC. CERN PH
Seminar. 29th Nov. 04
?

• Unfilled Araldite 2011 shows the highest
  thermal dilatation
• Stycast 1266 reduces its thermal dilatation by
  a factor 1.5 when filled to 40
• By filling, the integral thermal dilatation of
  the epoxy can nearly match that of metals !

13
? THERMOELASTIC DESIGN OF A CRYOGENIC MODULE ?
FILLED EPOXIES Cryogenic Silicon Microstrip
Detector Modules for Upgraded LHC. CERN PH
Seminar. 29th Nov. 04
Measurement of the mechanical properties of
unfilled radiation hard epoxies as a function of
temperature ? CERN EST
Young Modulus
Elongation at break
Tensile Strength
300 K 77 K
Araldite 2011 21.1 10.3 1.8 0.4
GPa 33.2 5.2 MPa 0.7 0.2 14.3 5.3
GPa 67.8 11.7 MPa Stycast 1266 1.2 0.4
3.2 0.3 GPa 58.9 2.8 MPa 0.8 0.5
11.0 3.0 GPa 120.0 11.6 MPa Type L 1.6
0.5 2.6 0.9 GPa 65.0 2.6 MPa 0.4 0.2
15.5 4.9 GPa 106.3 17.1 MPa

• Loss of ductility at low temperature (77 K)
• Young Modulus 3 to 8 times higher
• Reduction of elongation at break
• Increase of the Tensile Strength

Similar effects when filled
Unfilled Araldite 2011 was chosen for prototype
assembly Simulations with measured data show a
critical glue layer around 500 µm
14
? THERMOELASTIC DESIGN OF A CRYOGENIC MODULE ?
FILLED EPOXIES Cryogenic Silicon Microstrip
Detector Modules for Upgraded LHC. CERN PH
Seminar. 29th Nov. 04
Comparison with theoretical models
Hamilton, Greene and Davidson Linear dependence
of ? with the filling factor
Hartwig Model
Kerner Model
Tensor analysis Contact filler-epoxy Stress in
the epoxy and interface Elastic Linear
behaviour Efillgtgt Eresin ? Linear dependence with
?
15
? THERMOELASTIC DESIGN OF A CRYOGENIC MODULE ?
ALIGNMENT Cryogenic Silicon Microstrip Detector
Modules for Upgraded LHC. CERN PH Seminar. 29th
Nov. 04
16
? THERMOELASTIC DESIGN OF A CRYOGENIC MODULE ?
ALIGNMENT Cryogenic Silicon Microstrip Detector
Modules for Upgraded LHC. CERN PH Seminar. 29th
Nov. 04
17
? THERMOELASTIC DESIGN OF A CRYOGENIC MODULE ?
ALIGNMENT Cryogenic Silicon Microstrip Detector
Modules for Upgraded LHC. CERN PH Seminar. 29th
Nov. 04
Alignment of the module components
Special tooling was designed to embed the
micropipe into the carbon fiber composite
spacer No high precision in pipe position
18
? THERMOELASTIC DESIGN OF A CRYOGENIC MODULE ?
ALIGNMENT Cryogenic Silicon Microstrip Detector
Modules for Upgraded LHC. CERN PH Seminar. 29th
Nov. 04
Alignment of the module with respect to the beam

• Module is attached to a warm plate with thermally
  isolating precision support posts at three points
  
• Allow movement of the module while cooling down
  in x direction
• Minimize the thermal load thin wall cylinder
  re-entrant structure in stainless steel (30 mW)
• Position two precision holes
• Fixation two threaded holes
• Heat load absorbed at the attachment points by
  the cooling pipes
• Cryostat built following all these alignment
  principles

23 mm
19
? THERMOELASTIC DESIGN OF A CRYOGENIC MODULE ?
THERMAL TESTS Cryogenic Silicon Microstrip
Detector Modules for Upgraded LHC. CERN PH
Seminar. 29th Nov. 04
Goals Validate thermoelastic design
principles Thermal behavior of the module (T
distribution as a function of heat load, m,
x) Comparison with ANSYS simulations validation
or re-calibration
Experimental setup heat transfer in microtubes
? warm ? compressor circuit two-phase
Argon ? ? cold ? vacuum chamber ? IHX ? cold
finger ? Mechanical module Silicon sensor (3
x 3 cm), PA and support plate Al2O3 hybrid
CuNi pipe (0.5 ID) embedded CFC spacer
Araldite 2011 glue layers (100-300 µm)
thermal interface
cold finger
IHX
pre-heater
mechanical module
Heaters and Temperature sensors distribution in
the module
20
? THERMOELASTIC DESIGN OF A CRYOGENIC MODULE ?
THERMAL TESTS Cryogenic Silicon Microstrip
Detector Modules for Upgraded LHC. CERN PH
Seminar. 29th Nov. 04
Temperature distribution along the module as a
function of the mass flow rate and heat load
applied in the electronics/radiation
Tests with low (30 mg/s) and high mass flow rates
(120 mg/s) Tests with thermal radiation Evaluation
of the pressure drop with homogeneous model
Linear dependence of the T with heat
load Maximum ?T of 23 K at the AVP25 Thermal
radiation and m induce only marginal
differences Negligible variations of the HTC with
heat load or mass flow rate with respect to the
glue layers, which are the dominant thermal
resistance in the module Silicon is an excellent
heat spreader
?T 23.2 K
?T 15.7 K
?T 7 K
?T 4 K
Experimental conditions m 30 mg/s ? PPH 1.9
W ? xin0.2 ? PAPV25 0 2.4 W ? PRAD 0 W ?
xout 0.2-0.85 ?T measured with respect to Ar
bulk T
21
? THERMOELASTIC DESIGN OF A CRYOGENIC MODULE ?
THERMAL TESTS Cryogenic Silicon Microstrip
Detector Modules for Upgraded LHC. CERN PH
Seminar. 29th Nov. 04
Influence of the inlet vapor fraction in the
temperature distribution along the module
The temperature at the module is nearly constant
with the quality factor The dependence of HTC
with x is negligible compared to the thermal
resistance of glue layers There is no problem to
put modules in series !
Experimental conditions m 60 mg/s ? PPH 3-7
W ? xin0.1-0.6 ? PAPV25 1.77 W ? xout
0.1-0.85
22
? THERMOELASTIC DESIGN OF A CRYOGENIC MODULE ?
THERMAL TESTS Cryogenic Silicon Microstrip
Detector Modules for Upgraded LHC. CERN PH
Seminar. 29th Nov. 04
Stability of the cooling system
23
? THERMOELASTIC DESIGN OF A CRYOGENIC MODULE ?
THERMAL TESTS Cryogenic Silicon Microstrip
Detector Modules for Upgraded LHC. CERN PH
Seminar. 29th Nov. 04

• Comparison between simulations and tests
• Modifications on the ANSYS model to reproduce
  exact working conditions
• accurate geometry of the spacer
• glue layer thickness
• heat load distribution at ceramic heaters
• HTC ? xin 0.2 ? xout 0.75 ? HTC 9160,
  9186, 9216, 9247, 9274 W/m2 K

24
? THERMOELASTIC DESIGN OF A CRYOGENIC MODULE ?
THERMAL TESTS Cryogenic Silicon Microstrip
Detector Modules for Upgraded LHC. CERN PH
Seminar. 29th Nov. 04
Comparison between simulations and tests
calculation of mean heat transfer coefficient

• Determine the flow regime
• Mean heat transfer coefficient in twophase flow
• Heat transfer coefficient in single-phase flow
• Turbulent flow (Dittus-Boelter)
• Transition region (Hausen)
• Laminar flow

convective boiling nucleate boiling
25
? THERMOELASTIC DESIGN OF A CRYOGENIC MODULE ?
THERMAL TESTS Cryogenic Silicon Microstrip
Detector Modules for Upgraded LHC. CERN PH
Seminar. 29th Nov. 04
Comparison between simulations and tests
The T distribution along the module can be
described with a reasonable accuracy Linear
dependence of T with heat load Systematic
differences between simulation and tests (only 1
K !) CFC spacer can only be modeled to a certain
extent
26
? ASSEMBLY OF A FIRST PROTOTYPE WITH REAL
COMPONENTS Cryogenic Silicon Microstrip Detector
Modules for Upgraded LHC. CERN PH Seminar. 29th
Nov. 04
Assembly of a module with a large sensor FZ
Silicon sensor with active area 32.5 cm2 ? 500 ?m
thick ? 50 ?m pitch ? designed and processed at
the Microelectronics Center of the HIP
V-I characteristics of the sensor Fz - 1 ?A at
1000 V Cz 3 ?A at 900 V Full depletion at 320
V (Fz) and 420 V (Cz) Resistivity of 2-3 k? cm
(Fz)
27
? ASSEMBLY OF A FIRST PROTOTYPE WITH REAL
COMPONENTS Cryogenic Silicon Microstrip Detector
Modules for Upgraded LHC. CERN PH Seminar. 29th
Nov. 04
Assembly of a module with a large sensor
APV25 side (44 mm pad pitch) Silicon Sensor side
(50 mm)
CMS hybrid laminated in ceramics, 4 APV25 chips
characterization at low T Design of the support
plate and PA in silicon together with J.Härkönen,
processed at HIP Support plate 1 x 1 mm pad for
bonding. Metalization along the sensor is 2 mm
wide Bonding tests Design of a HV filter
28
? CHARACTERIZATION OF THE ELECTRONICS AT LOW
TEMPERATURE Cryogenic Silicon Microstrip Detector
Modules for Upgraded LHC. CERN PH Seminar. 29th
Nov. 04
Characterization of the CMS Hybrid at low
temperature
Heater and temperature feedthrough
Vacuum lines
Thermal isolation
Cryostat cover
Copper leads
Copper chuck where the hybrid is sitting
Power supplies
FED / VUTRI / FEC cards CMS like software to
read APV25
Cryostat vessel with an open bath of LN2
29
? CHARACTERIZATION OF THE ELECTRONICS AT LOW
TEMPERATURE Cryogenic Silicon Microstrip Detector
Modules for Upgraded LHC. CERN PH Seminar. 29th
Nov. 04
Pedestal, noise and pulse shape at low
temperature CMS Hybrid
Peak inverter off

• Increase of the signal height
• Lower rise time
• Lower noise
• with decreasing temperature

Peak inverter off
Peak inverter off
Deconvolution inverter off
30
? CHARACTERIZATION OF THE ELECTRONICS AT LOW
TEMPERATURE Cryogenic Silicon Microstrip Detector
Modules for Upgraded LHC. CERN PH Seminar. 29th
Nov. 04
Pedestal, noise and pulse shape at low
temperature Full Cryogenic Module
Tests carried out in Louvain by X. Rouby and
O.Militaru (November 2004) The setup was
slightly modified (allow HV line and RH
measurement) Module biased at 200 V, showing a
leakage current of 40 mA
31
? CRYOGENIC SI MICROSTRIP DETECTOR MODULES FOR
UPGRADED LHC Cryogenic Silicon Microstrip
Detector Modules for Upgraded LHC. CERN PH
Seminar. 29th Nov. 04
This work proposes a cryogenic module concept
which has the features for the microstrip
trackers of the upgraded LHC experiments at
CERN Such a module can hold an edgeless sensor,
being a good candidate for luminosity and total
cross-section measurements in the LHC
experiments First prototypes have been
assembled. The module is fully functional from a
thermoelastic point of view down to cryogenic
temperatures The readout electronics can be
operated down to 210 K. Further studies are being
carried out by RD39 members in Louvain-CERN A
series of modules with large and edgeless silicon
sensors are being assembled in order to be fully
characterized at low temperatures
32
The thermoelastic design is guided by the
properties of the silicon sensor and readout
chips. Silicon is an excellent heat spreader at
low temperatures and will be used as a structural
material support plate and pitch
adapter Evaporative cooling in microtubes
provides ideal thermal separation of the heat
source from the sensor and leads to a very
homogeneous temperature profile in the module
with minor impact Considerable reduction of the
module thickness with respect to the state-of-art
modules Future designs may include hybrids on
silicon and microchannels directly embedded on
the support plate Alignment and gluing jigs
have been designed, produced and successfully
tested The alignment of the detector with
respect to the beam is done through insulating
precision support posts and warm intermediate
plates
33
Thermal tests have validated the thermoelastic
design and proven that the cooling system is
stable. The glue layer is the dominating thermal
resistance in the module For a good
thermoelastic performace, thin continuous layers
are desirable. The adhesive layers should not
exceed 500 ?m The thermoelastic properties of
filled and unfilled epoxies have been measured as
a function of temperature Unfilled Araldite
2011 has been chosen for prototype assembly A
module with real components was assembled and
tested The readout electronics was characterized
down to 210 K, showing a decrease of noise, of
rise time and an increase of pulse height with
decreasing temperature A pair of edgeless
silicon pad sensors have been characterized with
a high energy beam. There is no evidence of dead
layer within the statistical accuracy of 8 ?m and
systematic accuracy of 6 ?m
34
? CRYOGENIC SI MICROSTRIP DETECTOR MODULES FOR
UPGRADED LHC Cryogenic Silicon Microstrip
Detector Modules for Upgraded LHC. CERN PH
Seminar. 29th Nov. 04
? DIRECTORS ? T.O. Niinikoski F. Calviño
? COOLING ? S. Grohmann G. Nuessle
? TOTEM ? W. Kienzle K. Eggert G. Matthia
TECHNICAL SUPPORT CRYOLAB ? J.M. Rieubland G.
Vandoni A. Vacca L.Dufay J. Gay L. le Mao, S.
Prunet, G. Ratcliffe H. Vigier ? TOOLING ?
R.Fortin N.Buil LAB INFRAESTRUCTURE BONDING ?
J.M. Avondo F.Cossey I. Mc.Gill C. Joram ?
GLUING ? A. Braem C. David D. Fraissard ?
MECHANICAL TESTS EPOXIES ? M.L.Delsante Y.
Forestier C.Hauviller R. Macías A.Perrin
S.Sgobba ? CFC ? A. Folley ? ANSYS ? M.Oriunno B.
Calcagno ? CMS HYBRIDS ? A. Cattai A. Honma
G.Rolandi P. Luukka O. Militaru X. Rouby A.
Marchioro W. Beaumont C. Millerin R. de
Oliveira N. Wauquier ? SILICON SENSORS ? Z. Li
J.Härkönen ? BEAM TESTS ? L. Casagrande V.
Granata E. Grioriev E. Heijne S. Klauke P.
Rato P. Sousa ? CMS TRACKER ? L. Mirabito P.
Siegrist B. Trocmé L. Silvestris T.Boccali ?
DATA ANALYSIS ? L. Gatignon V. Kärimaki J. Rico
? SEMICONDUCTORS ? J. Lozano