1. - chambers & absorbers -
Hcal internal design
- chambers & absorbers -
Engineering meeting
June 2008, 4th

2. Study of a new Hcal geometry…
Projective configuration
Tilted & optimized configuration
Same internal & external boundaries (2 regular dodecagons)

3. Study of a new Hcal geometry…
Tilted & optimized configuration
Proposition of Marco
- SLAC -
Zoom inside a trapezoidal module

4. Study of a new Hcal geometry…
Zoom inside a trapezoidal module
Proposition of Marco
- SLAC -
Screws

5. Study of a new Hcal geometry…
Picture without chambers
Allowable stresses ?
Will be checked by FEA…

6. Study of a new Hcal geometry…
Holes for chambers of 5mm in Marco’s drawings
5mm
5mm is a very small size (too small ?)
Is it realistic ?
Thickness of chambers + clearance to insert chambers !
8 + 2 = 10 mm

7. Study of a new Hcal geometry…
No machining of plates !
Not plane shapes after machining thin plates…
NB: machining would delete ≈ 30 % of material
Increase of cost for “nothing”…

8. Study of a new Hcal geometry…
A module can be a mechanical product of glued plates
Plates glued on all their faces (not screwed !...)

9. Tendency to have an internal projective layout !!!
Study of a new Hcal geometry…
Same idea for rectangle module : decrease of the tilt level…
Chambers layout in rectangle module
Crack ?
Particles trajectory
Tendency to have an internal projective layout !!!

10. Study of a new Hcal geometry…
Effective detection volume not the same than the volume of chambers (mechanics along the edges of the chambers)
Non detective volume of the chamber
Need of an overlap to avoid possible crack !
Probably increase of stresses level in this region
(thin and “long” region)
Compute FEA …

11. Study of a new Hcal geometry…
Hcal thickness
Max plate width
Stainless steel
Brass
λss = mm
λbrass = mm
λss / λbrass = / =
The HCAL thickness will be smaller for brass than for SS,
but the difference is really not very great !!!

12. ONLY depends on the material !!!
Study of a new Hcal geometry…
Max displacement under flexion :
f = 5 p L4 / (384 EI)
p : mass per length unit
L : width
E : Young modulus
I : inertia (mm4)
g = 9.81 m/s²
e : thickness of plates
ρ : volumic mass (kg/m3) p
( Pinned-pinned beam )
Max displacement can be written like this:
f = (5g / 32e²) * (ρ*L4 / E)
Constant
(doesn’t depend on the material)
ONLY depends on the material !!!

13. Study of a new Hcal geometry…
Max displacement can be written like this:
f = (5g / 32e²) * (ρ*L4 / E)
Stainless Steel
Brass
(ρ*L4 / E) = 7850 * (1841)4 / =
(ρ*L4 / E) = 8500 * (1813)4 / 1.1*1011 =
x 1.85
Despite a smaller interaction length for brass, and thus a smaller max width plate, it is not small enough to reduce the plates width.
The main drawback of brass comes from its small Young modulus (& allowable stresses will be smaller than SS)

14. Study of a new Hcal geometry…
PhD student will compute physics simulation on no projective Hcal design
I will write a summary of the status and our feelings & our concerns and send it to you…
Would you like to come at LAPP for a global meeting about Hcal ?