1. for a scintillator based MTT
Jens Frangenheim
III. Physikalisches Institut A
RWTH Aachen University
CMS Upgrade Workshop at FNAL, 2008/11/19 to 2008/11/21 Muon Detector Working Group, Thursday, 2008/11/20 09:40
Specific interests
of German groups
Hardware development
for a scintillator based MTT
General detector development plans
Aachen IIIA / IIIB and DESY collaboration
Associated work
First steps

2. use scintillator based MTT
general detector development plans
Muon fast Track Tag
idea: Bologna
muon system + absorption by calorimeter and coil
- tracks affected by multiple scattering
+ redundancy given by RPCs
tracker - huge number of tracks
+ precise pt measurement (high resolution, less material, strong B-field)
muon tag
use a new part of muon system (MTT) to select an interesting region in the tracker in L1-trigger
calorimeter
one option:
use scintillator based MTT
tracker
by A. Montanari
also Aachen III, DESY
in addition to Bologna

3. MTT design – German focus
general detector development plans
MTT design – German focus
based on the MTT idea including dimensions develop
scintillator detector
CMS Upgrade document n / A. Montanari
German groups focusing on detector development and building
(long tradition in Aachen)
(slide 18 from Pierluigi`s talk)

4. MTT hardware – dedicated technology
general detector development plans
MTT hardware – dedicated technology
Idea: Scintillator based MTT readout by SiliconPhotoMultipliers
maintenance free
no gas needed
very fast
any requested resolution possible
no HV needed (Usupply < 100 V)
less power needed (< 0.2 mW/mm2)
very good timing (100 ps to 1 ns)
high photon detection efficiency (up to 65 %)
but high noise rate (up to 1 MHz/mm2 at 0.5 PE threshold) and small active surface (up to 3 mm x 3mm at the moment)
Best suited device for triggering at the moment:
- highest photon detection efficiency
- low noise
- will soon be produced in CMOS technology (cheap)
Hamamatsu SiPM:
100 µm x 100 µm pixels

5. Aachen IIIA / IIIB and DESY collaboration
Aachen IIIA: - simulations about light collection /SiPM signal timing combining MTT with muon chamber
Aachen IIIB: - experience from tracker development SiPM supply electronics development
Aachen IIIA + Aachen IIIB: (finally) building the MTT
DESY: HCAL group member, possible integration with HO

6. MTT at Aachen IIIA – Scintillator designs
Aachen IIIA / IIIB and DESY collaboration
MTT at Aachen IIIA – Scintillator designs
Two possible designs:
“Traditional” one:
scintillator plates with embedded WaveLengthShifting fibers + light collecting in WLS fiber
→ more light/photon detector surface - mechanical effort
o good time resolution
“New” one:
SiPMs directly mounted to scintillator plates (was done with huge PMs) o low light yield - but readout perhaps possible (high pde, large SiPMs (~ price as smaller ones)
+ simple mechanical construction + very good time resolution - maybe more readout channels, power consumption
WLS fiber
(green light)‏
scintillator (blue light)‏
photon detectors
Aachen

7. MTT at Aachen IIIA – Light collection studies
Aachen IIIA / IIIB and DESY collaboration
MTT at Aachen IIIA – Light collection studies
- try to find best position of SiPMs, wrapping of scintillator, shape of WLS fiber
- have developed “standalone“ scintillator + SiPM simulation
- diploma student is working on GEANT simulation
diffuse reflection
“normal” reflection
total reflection
Aachen IIIA cosmics testing (student project)

8. Aachen IIIA / IIIB and DESY collaboration
MTT at Aachen IIIB
Aachen IIIB brings in experience from tracker (petals) assembling / testing:
- one focus: development of compact SiPM readout electronics - especially: development of a gain stabilization on a chip (SiPM gain is
temperature and maybe time and radiation dose
dependent)
Aachen IIIB SiPM-cosmics testing

9. MTT at Aachen – common Aachen IIIA/B parts
Aachen IIIA / IIIB and DESY collaboration
MTT at Aachen – common Aachen IIIA/B parts
timing (kind of coincidence, time resolution)
(trigger) electronics tests
build large test detectors
tests together with other detectors (muon chamber, petal)
SiPM mounted on Aachen pcb, first test with scintillator
tracker petal
CMS silicon petal
quality control
at Aachen IIlB
cosmic muon
MTT test detector
muon chamber

10. MTT at DESY - DESY member of HCAL group (CASTOR)
Aachen IIIA / IIIB and DESY collaboration
MTT at DESY
- DESY member of HCAL group (CASTOR)
- interested in combination MTT with HO
- change of HPD in SiPM for HO needed → exchange of initial two readout-boxes planned for this shut down → get experience with the longterm operation with SiPM (new detector technology, also at T2K starting 2009)
- further discussion between Muon and HCAL groups underway, need experiences with HO with SiPMs and for sure simulations everywhere

11. associated work
Associated work

12. Implementation of MTT into CMSSW
associated work
Implementation of MTT into CMSSW
Scintillator very sensitive to background !
scintillator can probably not distinguish between kinds of particles
scintillator does not measure momenta
MIP produce less light than background (e.g. slow protons, electrons)
background rate of all (charged) particles including low momentum particles
timing of background (and signal)
momentum of background particles (absorbing / producing secondary particles)

13. Strategies to limit sensitivity of MTT to background
associated work
Strategies to limit sensitivity of MTT to background
slow e-
pion
Absorber (thin, between 2 scintillator layers): Absorbs low momentum particles between the two layers. → MTT gets too thick ? Two layers too expensive ?
Use multiple scattering/magnetic field deflection
→ Does not work with one MTT element.
Set time-of-flight gate: Reduce sensitivity to neutron background, slow pions and kaons → Need high time resolution, more electronics ?
Set pulse height amplitude (=amount of light) limit: (background produces mostly more light than MIPs)
Combination with HO
MTT layer 1
absorber (Pb)
MTT layer 2
new
particles
neutron induced proton

14. first steps
First steps

15. Simplest scintillator based detector
first steps
Simplest scintillator based detector
SiPMs directly coupled to front side of a piece of scintillator
+ very simple set up
+ thin construction
+ very good time resolution
- a lot of SiPMs needed
- many readout channels (but high resolution)
100 mm
Aachen
idea: T.H. for SLHC
SiPMs (3 mm x 3 mm)
in unconventional position

16. Simulation results (2) 4 PE threshold
first steps
Simulation results (2)
Assuming: % diffuse reflexion at surrounding 3M tape
- 3 mm x 3mm detectors % photon detection efficiency (80 % coupling efficiency)
4 PE threshold

17. Simulation results (2) no correlation with SiPM position visible
first steps
Simulation results (2)
need 2 of 4 coincidence
(4 PET for each SiPM)
noise rate < 1 Hz
no correlation with SiPM position visible
efficiency > 80 % for 10 mm thick scintillators
(gets ~ 100 % for 95 % reflective wrapping)
position of SiPM
(to be tested with larger scintillators)

18. Simulation for WLS fiber setup (1)
first steps
WLS fiber simulation
Simulation for WLS fiber setup (1)
SiPMs
(Hamamatsu 100 pixels,
1 mm x 1 mm)
WLS fiber (BCF-92)
piece of scintillator (BC-404)
100 )
simulated muons traverses 10
100
- uniform distributed, vertical particle transition
- require coincidence (interval < 10 ns) between both SiPMs with 3 PET
→ noise rate < 1 Hz

19. Simulation for WLS fiber setup (2)
first steps
Simulation for WLS fiber setup (2)
light collection effect of WLS fiber huge
more than 98 % detection efficiency
(using 1 mm x 1 mm SiPMs)
time resolution of detector still good

20. conclusion
Conclusion
MTT is a promising concept to include tracker data into L1 muon trigger: - DT and RPC can be kept as independent systems MTT can also solve DT occupancy problem (at L1-trigger).
Scintillator based MTT could be an easy and cheap solution: - It can be inserted in addition to existing detectors SiPMs are a very promising technology German groups can contribute to detector development and building MTT/HO: under discussion, several aspects to be clarified
At SLHC may need any kind of redundancy !