2014-08-19-Shai

Report
Thermal Analysis of the C200
Calorimeter
Shai Ehrmann
California State University, Los Angeles
Tasks Accomplished July - August
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Prepared and repaired 250 PMTs for GRINCH
Removed 50 PMTs for HCAL from Big HAND
Measured flatness of HCAL scintillator sample
Studied 100 light guides for ECAL by measuring flatness and perpendicularity
Conducted experimental study of thermal conductance and cooling of light guides
Calculated thermal properties of ECAL
– Temperature gradients
– Heating and cooling times
Researched heat induced transparency loss
Conducted thermal annealing experiments
Began 3D thermal analysis of ECAL
– Prepared input files
– Assisted Silviu Covrig with ANSYS analysis
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What is the C200 calorimeter?
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Designed to maintain permanent heat annealing to lead glass blocks.
3
What is the C200 calorimeter?
•
Designed to maintain permanent heat annealing to lead glass blocks.
•
Calorimeter receives heat from several heaters to ideally maintain a 1-dimensional linear
temperature gradient. The entire system is insulated on all sides.
4
What is the C200 calorimeter?
•
Designed to maintain permanent heat annealing to lead glass blocks.
•
Calorimeter receives heat from several heaters to ideally maintain a 1-dimensional linear
temperature gradient. The entire system is insulated on all sides.
•
Calorimeter is comprised of lead glass blocks attached to light guides, which provide a
cooling temperature gradient for proper PMT functioning.
*Q(A) and Q(B) denote the desired direction of heat flux
5
What is the C200 calorimeter?
•
Designed to maintain permanent heat annealing to lead glass blocks.
•
Calorimeter receives heat from several heaters to ideally maintain a 1-dimensional linear
temperature gradient. The entire system is insulated on all sides.
•
Calorimeter is comprised of lead glass blocks attached to light guides, which provide a
cooling temperature gradient for proper PMT functioning.
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Lead glass blocks are organized in a 20x20 array, while light guides are organized in a
skewed 10x20 array.
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Primary Heat Analysis
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Thermal analysis is essential to ensure design feasibility and efficiency.
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Primary Heat Analysis
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Thermal analysis is essential to ensure design feasibility and efficiency.
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Heat is provided from a main heater to achieve Q(A) and from an auxiliary heater to achieve
Q(B), which together administer an appropriate temperature gradient throughout the
system.
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Primary Heat Analysis
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Thermal analysis is essential to ensure design feasibility and efficiency.
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Heat is provided from a main heater to achieve Q(A) and from an auxiliary heater to achieve
Q(B), which together administer an appropriate temperature gradient throughout the
system.
Desired Temperatures:
Surface A → 225 °C
Surface B → 175 °C
Surface C → 50 °C
Corresponding Heat Required:
() = 0.16   
() = 0.46   
∑  = 64 
∑  = 92 
 = ∑  + ∑  = 156 
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Primary heat analysis shows that the regime requires a net power of 156 W.
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Light Guide Temperature Gradient Study
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Goal: to test cooling at PMT and to study heat transfer in the light
guide.
*Light guide with approximately 2 cm of wool glass insulation
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Light Guide Temperature Gradient Study
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Goal: to test cooling at PMT and to study heat transfer in the light
guide.
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We attach a copper radiator to amplify cooling effect.
*The copper radiator acts as a heat exchanger to ensure
and maintain appropriate temperature at cool end.
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Light Guide Temperature Gradient Study
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Goal: to test cooling at PMT and to study heat transfer in the light
guide.
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We attach a copper radiator to amplify cooling effect.
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Results verify the efficacy of a copper radiator in cooling; as T1
approached 200 ᵒC, T3 remained below 40 ᵒC.
T1
T2
T3
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Heat up and cool down
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For experiment logistics and safety we assess the amount of time necessary to heat up the
C200 calorimeter and the effects of cool down.
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Heat up and cool down
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For experiment logistics and safety we assess the amount of time necessary to heat up the
C200 calorimeter and the effects of cool down.
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Solving the heat equation for the specific thermal system, we find that the regime of
lead glass heating will ideally achieve a thermal gradient within 1% of equilibrium in 75
hours, within 5% in 40 hours, and within 10% in 30 hours.
Time-Based Temperature Profile
Initial Profile
10 hours, 50% Equilibrium
30 hours, 90% Equilibrium
40 hours, 95% Equilibrium
75 hours, 99% Equilibrium
225 ᵒC
Lead Glass
175 ᵒC
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Heat up and cool down
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Cool down in the case of immediate shut off will primarily occur by convection and
conduction through the light guides due to low thermal conductivity in foam glass
insulation.

 = . 
∙
Foam Glass Insulation
Lead Glass
Light Guide
 = . 

∙
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Heat up and cool down
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Cool down in the case of immediate shut off will primarily occur by convection and
conduction through the light guides due to low thermal conductivity in foam glass
insulation.
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Analysis shows that the temperature gradient in the calorimeter will reach
approximately 10 ᵒC/cm at the onset of cooling and will relax until reaching room
temperature.
225 ᵒC
175ᵒC
50ᵒC
Lead Glass
Light Guide
Expansion Cycles
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Steel bracing will expand more rapidly and with greater magnitude than lead glass during heat up.
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Expansion Cycles
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Steel bracing will expand more rapidly and with greater magnitude than lead glass during heat up.
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Expansion is relatively minimal, and should not compromise the mechanical integrity of the
calorimeter.
∆L = 0.15 mm
∆L = 1 mm
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Expansion Cycles
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Steel bracing will expand more rapidly and with greater magnitude than lead glass during heat up.
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Expansion is relatively minimal, and should not compromise the mechanical integrity of the
calorimeter.
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The effective linear thermal expansion between the surfaces of lead glass and the surfaces of
steel bracing will create a gap of 1.4 mm on the sides and 3 mm on the top. These gaps will be
mediated with spring bracing to maintain compression on the lead glass array.
∆L = 3 mm
∆L = 1.4 mm
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Expansion Cycles
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Steel bracing will expand more rapidly and with greater magnitude than lead glass during heat up.
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Expansion is relatively minimal, and should not compromise the mechanical integrity of the
calorimeter.
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The effective linear thermal expansion between the surfaces of lead glass and the surfaces of
steel bracing will create a gap of 1.4 mm on the sides and 3 mm on the top. These gaps will be
mediated with spring bracing to maintain compression on the lead glass array.
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During the cooling cycle, steel will contract more rapidly. The peripheral blocks of lead glass will
contract more quickly than the inner blocks and leave small gaps due to shrinking.
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Lead Glass Annealing
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Goal: to study the relationship between annealing time, temperature and effectiveness in
reducing radiation damage.
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Lead Glass Annealing
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Goal: to study the relationship between annealing time, temperature and effectiveness in
reducing radiation damage.
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Data was taken for lead glass blocks at various durations and temperatures of heat soaking to
measure the magnitude of damage reduction. Results verify that annealing temperature and
annealing duration are both important factors in eliminating radiation damage.
Block
Temperature
[ ᵒC]
Duration
[Hours]
Damage Reduction
Factor
A
B
C
D
E
200
200
250
225
225
4
2
4
2
8
11.22
3.60
66.72
25.23
58.50
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Lead Glass Annealing
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Goal: to study the relationship between annealing time, temperature and effectiveness in
reducing radiation damage.
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Data was taken for lead glass blocks at various durations and temperatures of heat soaking to
measure the magnitude of damage reduction. Results verify that annealing temperature and
annealing duration are both important factors in eliminating radiation damage.
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Several blocks were re-annealed in order to attain maximum transparency. Results showed
that blocks do not have the same base absorption.
Block
C
D
E
Temperature
[ ᵒC]
225
250
250
225
Re-anneal Data
Duration
[Hours]
12
12
16
12
Base Absorption
[µA]
~ 0.5
~ 0.7
~ 0.75
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Conclusion
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The study of thermal annealing of lead glass blocks allows us to quantify the radiation
damage reduction.
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Conclusion
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The study of thermal annealing of lead glass blocks allows us to quantify the radiation
damage reduction.
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During heating and cooling cycles, the C200 design maintains mechanical stability.
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Conclusion
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The study of thermal annealing of lead glass blocks allows us to quantify the radiation
damage reduction.
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During heating and cooling cycles, the C200 design maintains mechanical stability.
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The net heat loss through insulation is approximated at 225 W; however the real heat loss
will be much greater due to insulation gaps and bracing design. We can thus estimate
that the heaters should generate at least 1 kW.
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Conclusion
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The study of thermal annealing of lead glass blocks allows us to quantify the radiation
damage reduction.
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During heating and cooling cycles, the C200 design maintains mechanical stability.
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The net heat loss through insulation is approximated at 225 W; however the real heat loss
will be much greater due to insulation gaps and bracing design. We can thus estimate
that the heaters should generate at least 1 kW.
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The light guides measured for flatness and perpendicularity are of adequate quality to
allow for proper attachment to lead glass and to PMTs.
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