Scintillating Tiles for the Muon Inner regions

LHCb Muon Upgrade meeting, CERN May 11 2012

Wander Baldini for the Ferrara LHCb group

The Idea W

LS fibers to SiPMs

• Tiles of scintillator with the dimension of the logic pads.

• Each pad is read out

through a WLS fiber and a SiPM

• Each tile of scintillator can be a few cm deep (4-5cm) in order to have a very high detection efficiency even with a single layer

• Thin aluminum foil among the tiles

Logic Pad

Beam

2

The Idea

• The fiber is housed in a groove machined on the surface of the tile

• The groove can be shaped so that the light collection is optimal (the easiest is the diagonal but also other shapes can be easily done)

• The SiPMs are places on the external perimeter of the chamber (if the radiation allows… see next slides)

WLS Fiber=f 1.2mm

Beam

Silicon Photo-Multiplier1.3x1.3 mm2

3

The Idea

• The scintillator can be put on the front layer

• SiPMs and FE electronics can be

located on the back layer (which would be completely free…)

• In this way we can control temperature of SiPMs and shield them from radiation (polyethylene+boron)

Scintillator

Bundle of fibers

SiPMs

Shielding + thermal insulation

FE Electronics

Beam

4

Detection efficiency • From R&D tests for SuperB:

– 1cm of extruded scintillator (FNAL-NICADD) – one WLS fiber Kuraray Y11(300), =f 1.2mm – SiPM from Hamamatsu 1.3x1.3mm2 we measure about 50 p.e./cm

• In our case, on average, the path inside the scintillator should be 1cm<x<4cm so we expect ~ 50 -200p.e. (more precise studies with toy MC are ongoing)

• Very preliminary results show a detection efficiency > 99.8% for 4cm deep tiles, if needed the depth can be increased

1cm

~ 0.6 cm parti

cle

particle

5

Costs estimate

• Scintillator: ~ 25 $/kg (FNAL NICADD)

• WLS Fibers: ~ 5 €/m

• SiPMs: ~ 18 €/each (Hamamatsu, the most expensive )

6

Cost estimate • M2R1 :

– 384 ch/chamber– SiPM 384/chamber – Fibers: ~ 30cm of fiber/channel 115 m/chamber – Active volume: 3 x 2.5 x 0.4 = 3 dm3 --> ~3 kg of scintillator/chamber scintill: 100 €, fibers: 600€, SiPMs: ~7k€ tot ~ 8k€/chamber – 12 chambers ~100k€

• M2R2 : – 192 ch/chamber– SiPM 192/chamber – Fibers 60m/chamber – Active volume: 6 x2.5 x 0.4 = 6 dm3 ~ 6 kg/chamber scintill: 200€, fibers: 300€, SiPMs: ~3.5k tot ~ 4k€/chamber – 24 chambers ~100k€

• M3R1 Same as M2R1 • M3R2 Same as M2R2

≈ 100 k€/station-region, 400 k€ total (M2-3,R1-2)

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A few considerations about SiPMs: • 90% of total cost is due to SiPMs• Hamamatsu are the most expensive, many others on the market

(FBK, SenSL ..) ≈30% cheaper (but more noisy, lower gain etc..) • SiPMs are very sensitive to radiation (especially neutrons)

– radiation damage test forseen in July at GELINA (IRMM- Geel, Belgium) on Hamamatsu, FBK, SenSL devices.

– shielding power of Polyethylene + Boron and Lithium will be studied– Test of few devices from Hamamatsu improved for radiation hardness– Test of scintillators, fibers, glue, optical grease

• This issue is particularly true for R1, if it turns out to be critical:

– Local shielding (Polyethylene + Boron or Lithium )– SiPMs could be put in a less hot region through longer WLS fibers (attenuation

length ~ 3.5m) or clear fibers (attenuation length ~ 10m).

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conclusions• The proposed technique seems to be promising:

– scintillators+fibers: • robust and reliable• Easy to build (a total of 72 chambers to be built for M2-3, R1-2), • Very fast response• Flexible: instead of single chambers a whole quadrant (3 chambers )

could be built as a single detector• No gas needed

– SiPMs: • fast response, performances rapidly improving (dark count

decreased by a factor 10 on Hamamatsu devices in the last 2 Years)• No need of H.V. (only ~70V for Hamamatsu, <35V for FBK,SenSL ) • Radiation damage to be studied, results expected in the summer• How to interface SiPM FE electronics with Muon Read Out to be

studied 9