scintillating tiles for the muon inner regions lhcb muon upgrade meeting, cern may 11 2012 wander...

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)

7

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).

8

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