Main Changes to the FT description:
Should be a TWiki page, extend knowledge of experts to others, include links
Zip file of material information brochures and MSDS:
MaterialsSafety.zip
Right-click -> 'View Image' to view larger image, or download the link from the bottom
Panel Materials:
- correct thicknesses and core materials(Oliver, Blake)
- realistic mats (Dortmund and Aachen to measure and weigh a produced mat), five layer and six layer mats
- panelassembly_sideview.pdf: panelassembly_sideview.pdf
- layers should be combined to reduce number of volumes, most materials have radiation lengths of ~40 g/cm2. i.e. incorporate the glue layers into the carbon fibre skin.
- 2 x 2mm endpiece material should be added at the y=0 region and around the beam pipe. See drawings below.
Material |
Thickness (μm) |
Layers |
X0/ρ (cm) |
X/X0 (%) |
Core(Nomex/Airex/Divinycell*) |
20000 |
2 |
1750/689/1050 |
0.229/0.580/0.381 |
CFRP skin |
200 |
2 |
27.56 |
0.145 |
Panel glue |
75 |
4 |
34.9 |
0.083 |
Fibre mat(w/TiO2) |
1450 +30/-100 (6 layers) |
1 |
33.2 |
0.437+0.01/-0.03 |
Casting glue(w/o TiO2) |
100 |
2 |
34.9 |
0.055 |
Total y>2cm |
4235 |
|
|
0.95/1.3/1.1 |
Polycarbonate |
2000 |
2 |
41.46 |
0.965 |
Total y<2cm** |
4235 |
|
|
1.79/2.11/1.93 |
*Divinycell is the preferred option for now
**core and casting glue are removed to accomodate endpiece
Elements and material radiation lengths
(taken from slides: Physics IB RWTH Aachen, A. Schultz v. Dratzig):
X
0 g/cm2 = 716.4*A/(Z(Z + 1)*ln(287.0/sqrt(Z)))
Element |
X0(g/cm2) |
H |
63.047 |
C |
42.70 |
N |
37.99 |
O |
34.24 |
F |
32.93 |
Ti |
16.17 |
1/X
0 = Σn
j/X
0j
Material |
Composition |
X0 g/cm2 |
Density (ρ) g/cm3 |
X0/ρ cm |
Epoxy |
C27 H32 O4 N2 |
41.87 |
1.2 |
34.89 |
Polycarbonate |
|
41.46 |
1.2 |
34.6 |
Airex R82.60 |
C37 H24 O6 N2 |
41.35 |
0.060 |
689.13 |
Divinycell F40 |
Airex-like |
42.0 |
0.040 |
1050 |
Nomex A1-24-6 |
C14 H10 O2 N2 + C8 H12 O2 |
42.0 |
0.024 |
1750 |
CFRP |
60%(68.75%)Fibre/40%(31.25) Epoxy by volume(weight) |
42.44 |
1.54 |
27.56 |
SciFi Mat w/TiO2 |
Double clad |
39.18 |
1.18 |
33.23 |
Epoxy = Bisphenol-A C15 H16 O2 + 2 Epichlorohydrine C3 H5 Cl O = C21 H26 O4 Cl2 +
NaOH –
NaCl –
H2O = C21 H24 O4 + Diaminobenzol C6 H8 N2 = C27 H32 O4 N2 X0 = 41.87 g/cm^2 = 34.89 cm
Radiation Length of
SciFi Mat:
- Polystyrene 58.58 % mass
- PMMA 4.32 % mass
- Fluorinated Polymer 5.32 % mass
- TiO2 7.94 % mass
- Epoxy 23.84 % mass
- X0 = 39.18 g/cm^2
Geometry
Notes:
- a higher resolution pdf of the sketches below is here panelassembly.pdf: panelassembly.pdf
- triangles stay as is (no horizontal y=0 cut); impact on efficiency being evaluated first
- Additional dead material at fibre mat edges
- (0.125mm of dead fibre at each outer edge of the fibre mat + 130.2mm of active fibre to match SiPM active width of 4 arrays) = 130.45 total mat width
- 0.150 mm between fibre mat edges = 130.60 mm centre-to-centre of adjacent mats; likely will be filled with epoxy resin during production.
- Module widths to match SiPM gaps and widths (522.4mm outer width of modules in X, stereo too)
- Layer position in z remains the same
- Beam pipe cut-out should be studied. Someone needs to find the optimal cutout. Will use SiPM array widths (32.650mm c-to-c as horozontal cut width. Step height will be determined by beam-pipe radius per station.) for now until optimal pattern is studied.

Beam-pipe region
- scifi beampipe layout:

Table from
https://lhcb-background.web.cern.ch/lhcb-background/BeamPipe/Drawings/August2007/Table-20070808.htm
Last edited by G. Corti 6-Mar-2006
Component |
Detail |
Zstart |
Zend |
Length |
Inner |
Inner |
Thickness |
Outer |
Height |
Outer |
Theta |
|
Dz |
Radius |
Diameter |
( c ) |
Radius |
(d) |
Diameter |
(d2) |
|
[mm] |
[mm] |
[mm] |
(a) [mm] |
(b) [mm] |
[mm] |
(a1) [mm] |
[mm] |
[mm] |
[mrad] |
Conical section |
see Split4 |
7500.05 |
8300.05 |
800.00 |
75.00 |
150.01 |
1.60 |
76.60 |
153.21 |
10.00 |
Conical section |
8300.05 |
8700.05 |
400.00 |
83.00 |
166.01 |
1.70 |
84.70 |
169.41 |
10.00 |
Conical section |
8700.05 |
9500.05 |
800.00 |
87.00 |
174.01 |
1.90 |
88.90 |
177.81 |
10.00 |
Conical section |
9500.05 |
10300.05 |
800.00 |
95.00 |
190.01 |
2.00 |
97.00 |
194.01 |
10.00 |
(a) |
Inner radius of the beam pipe for cones at Zstart |
(a1) |
Outer radius = |
Inner radius + radial thickness for pipes (approx with thickness when calculated) |
|
inner radius + height for flanges and bellows |
(b) |
Quoted for convenience |
(c) |
This is the thickness for the pipe wall. Details for the bellows are quoted separately in the additional table just above. |
(d) |
This value is valid only ffor flanges and refers to their radial dimension |
(d2) |
For flanges the angle applies only for the inner wall, the outer wall has 0.0 angle |

Station |
ZCentre |
ZLast-edge |
bp radius (e) |
bp thickness |
buffer |
module diam. |
|
[mm] |
[mm] |
[mm] (e) |
[mm] (f) |
[mm] (g) |
[mm] (h) |
T1 |
7948 |
8061.2 |
80.61 |
1.67 |
20 |
204.6 |
T2 |
8630 |
8743.2 |
87.43 |
1.91 |
20 |
218.7 |
T3 |
9315 |
9428.2 |
94.29 |
1.99 |
20 |
232.6 |
(e) |
inner beampipe radius at the last station edge |
(f) |
beam pipe thickness at last station edge |
(g) |
buffer is an estimated nominal value for now (May 27, 2014); will be updated in the future |
(h) |
station cutout to accommodate the beampipe including the 20mm buffer radius |
Digitization
- Photo Detector spacing (Diego, Guido)
- A SiPM array consists of (from left to right) 0.170 mm inactive edge + 16.00 mm 64ch active + 0.250 mm inactive gap + 16.00 mm 64ch active + 0.170 mm inactive edge = 32.59 mm total package width
- SiPM arrays are spaced 0.060mm apart such that adjacent SiPM arrays are 32.650mm centre-to-centre
- Dead spaces dues to inactive regions are then either 0.250 mm between 64chs, or 0.400 mm between neighbouring arrays (0.170mm +0.060mm +0.170mm)
- Modules are nominally spaced 3mm apart, same as the OT. Inactive regions between modules are then 3mm + 0.400 mm = 3.400 mm
- A fibre mat is 0.125 inactive material + 130.2mm active + 0.125 inactive material from left to right. The active material aligns with the outermost active channels of 4 SiPM arrays
- The gaps between fibre mats with a module align with the space between active SiPM arrays. 0.125mm inactive material + 0.150 mm gap + 0.125 mm inactive material = 0.400 mm
Module Spacing (mm) |
Geometrical Coverage by SiPMs |
0.0 |
98.0%* |
1.0 |
97.8% |
2.0 |
97.6% |
3.0 |
97.4% |
4.0 |
97.2% |
* there is a total of 10.4 mm of gaps (16*0.4mm + 16*0.25 ) within the 522.4mm
SiPM length in a module.
- Attenuation and radiation maps: parameterisation or tables. Needs to be explainable to other people in code, documentation or something.
- number of direct photons detected per MeV deposited (light yield, spectra, quantum efficiency, attenuation due to radiation, 0--50fb-1)
- number of reflected photons detected per MeV deposited (" ")
- Check geometrical efficiency not included in hit detection efficiency
- Light sharing and clusterisation:
- cosmic, Sr90 source(perpendiculer) vs Nikhef simulation(larger angular acceptance), equation that models multiplicity better
- *tails in the energy deposition, Birk's saturation, efficiency in low p.e. side; tune detailed GEANT mode
- Fluctuations: check for double application(smearing) of effects
- Noise model: all parameters need to be checked. Update and verify model i.e.
- Crosstalk percentage is currently 7%
- Afterpulsing is currently 15% probability, check temperature dependence of time constants and effect on spillover
- Dark count rate changes with overvoltage (proportional to volume of silicon in the depletion region)
- Check Thermal dark count rate (unirradiated) 100kHz?
- Check that damage with dose is correct
- Spillover
- Check with electronics people that the time dependant signal amplification is correct (currently only simulation)
HC: It is not correct (it has been done only with the Hamamatsu
SiPM model with an incomplete simulation model). New simulations have to be performed and checked with the real hardware.
-
- Optimization of t_0 needed to balance spillover?
Monte Carlo Sample Priority
Yasmine will add her table
- Additional geometric configurations: bilayer, y-segmentation will get lower priority over baseline detector studies.