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):

X₀ 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/X₀ = 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
  • = 33.23 cm

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.