1 Calorimeter 4-May-2009 Added Slides Data from MAS GCALOR with phojet min-bias events in ATLAS detector

2 3D Model of Calorimeter Al tube is modeled with shell elements. Its temperature is set to 90°K. It is eccentric mm gap on top 0.05 mm gap here Copper Matrix Tungsten Matrix Argon Copper

3 Al Tube Eccentricity Argon Copper matrix

4 Aluminum Shell and Argon Elements The aluminum shell, above, is wrapped around the OD. It is currently being used as a convenient surface to fix at 90°K. Plate elements are used. They are being plotted here as a surface (no thickness). Liquid argon is modeled with solid conduction elements as shown above. The aluminum shell plates the outer surface.

5 Conductivities Y X Z

6 Heat Generation Rate, W/mm^3

7

8 Steady State Temperatures, All Components

9 Steady State Temperatures, Argon Excluded

10 Steady State Temperatures, Argon Excluded This view demonstrates that the OD is held to 90°K

11 Steady State Temperatures, Argon Jacket Gradient 0.079° K through the 1.95 mm thick argon jacket here 0.012° K through the 0.05 mm thick argon jacket here

12 Mesh Refinement Checks (2D Models) BaselineTwice Refined Once Refined

13 Mesh Refinement Checks, Heat Generation A simplified spatial distribution of heat generation is used for these models. Units are W/mm 3

14 Mesh Refinement Checks Baseline Tmax = K Once Refined Tmax = K Twice Refined Tmax = K There is little change in the thermal solution as the mesh is refined. The discretization error is approximately 1.1% These results use a uniform OD gap of 1.95 mm

15 Comparison of 2D and 3D Results Using the specified distribution of heat generation in both models: –The 3D model result is: Max argon temperature90.147°K Max metal temperature °K –The 2 D model result is: With a uniform 1.95 mm gap at the OD –Max argon temperature90.188°K –Max metal temperature °K With a uniform 1 mm gap at the OD –Max argon temperature90.129°K –Max metal temperature °K These results suggest that in the 3D model heat is being conducted to the bottom of the collimator where the argon gap is small.

16 Kapton Wrap The modules are wrapped with 0.1 mm thick Kapton which has about the same conductivity as liquid argon. The previous results had an 0.05 mm liquid Argon layer at the bottom and a 1.95 mm layer on the top. The minimum layer thickness was increased to 0.1 mm. Comparing temperatures of a node near the OD at the bottom and top of the copper matrix (Al cylinder deflections are discussed on the following slides): As expected, the thicker insulating area at the bottom increases temperatures near the bottom by 0.01°C (83%). The temperature near the top increases by 0.002°C (2.5%) meaning that the slightly lower thermal resistance at the top is offset by the doubling of the thermal resistance at the bottom.

17 Temperatures with Kapton Wrap

18 Deformation of the Aluminum Cylinder Up to now the aluminum cylinder has been assumed to be rigid. Its ID is 2 mm larger (1.8 mm accounting for the Kapton wrap) than the module’s OD. The modules were displaced 0.9 mm downward leaving an 0.1 mm gap at the bottom and a 1.9 mm gap on top. Some deformation of the aluminum cylinder can be expected. To predict this I used a rigid cylinder to represent the modules and added disks to each end of the aluminum cylinder (these keep the ends round). Contact elements were used between the cylinder and modules.

19 Deformation of the Aluminum Cylinder Nodal forces indicating contact Rigid Contact Surface (the modules)

20 Clearance Between Modules and Cylinder The cylinder deforms to be closer to the modules from over the region extending to 52° from the bottom. Above 100° the cylinder deforms to move further from the modules than would be the case with a rigid cylinder. The effect on the thermal solution is increased heat transfer (the smaller gap at the bottom outweighs the larger gap at the top. The end of the cylinder is at Z=0 The midpoint is at Z=27.254”

21 Revised Temperatures, Kapton Wrap and Al Cylinder Deflection