1. HE CALORIMETER DETECTOR UPGRADE R&D
Y. Onel
for
University of Iowa
Fairfield University
University of Mississippi
SLHC Workshop at FNAL
November 19 – 21, 2008

2. HCAL Upgrades First Phase of the R&D
1st Phase of R&D
2nd Phase of R&D
Light enhancement tools: ZnO, PTP
Radiation damage tests on Quartz and PTP
3rd Phase of R&D
Alternative readout options:
PIN Diode, APD, SiPMT, MCP
Microchannel PMT, MPPC
Radiation Hard WLS Fiber options
Quartz core sputtered with ZnO
Sapphire fibers
First Phase of the R&D
Show that the proposed solution is feasible
Tests and simulations of QPCAL-1

3. The “Problem” and the “Solution”
As a solution to the radiation damage problem in SuperLHC conditions, quartz plates are proposed as a substitute for the scintillators at the Hadronic Endcap (HE) calorimeter.
Quartz plates will not be affected by high radiation. But the number of generated cerenkov photons are at the level of 1% of the scintillators.
Rad-hard quartz
Quartz in the form of fiber are
irradiated in Argonne IPNS for 313 hours.
The fibers were tested for optical degradation
before and after 17.6 Mrad of neutron and
73.5 Mrad of gamma radiation.
Polymicro manufactured a special
radiation hard anti solarization quartz plate.

4. Radiation Damage Tests on Quartz with 24 GeV protons
K. Cankocak et al., NIM A 585, 20-27, 2008
We investigated the darkening of two high OH content quartz fibers irradiated with 24 GeV protons at the Cern PS facility IRRAD.
The two tested fibers have a 0.6mm quartz core diameter, one with hard plastic cladding (qp) and the other with quartz cladding (qq).
These fibers were exposed at about 1.25 Grad in 3 weeks.
The fibers became opaque below 380nm and in the range 580–650 nm.
The darkening under irradiation and damage recovery after irradiation as a function of dose and time are similar to what we observed with electrons.
The typical attenuation at 455nm are 1:44 0:22 and 2:20 0:15 dB=m at 100 Mrad for qp and qq fibres, respectively. The maximum damage recovery is also observed near this wavelength.

5. Damage Recovery on Quartz
Along and after irradiation the quartz exhibits a peculiar behaviour in the transmission of the blue light (near 450 nm) compared to the transmission of UV light and near 600 nm:
Quite low absorption near 450 nm compared to high absorption below 380nm and near 600 nm.
Almost full recovery of the radiation damage near 450nm and no recovery after high dose irradiation, below 380nm and above 580nm.

6. 1st Paper : R&D Studies on Light Collection
As a solution to the radiation damage problem in SuperLHC conditions, quartz plates are proposed as a substitute for the scintillators at the Hadronic Endcap (HE) calorimeter.
The paper (CMS-NOTE 2007/019) summarizing the First Phase of the R&D studies has been published :
F. Duru et al. “CMS Hadronic EndCap Calorimeter Upgrade Studies for SLHC - Cerenkov Light Collection from Quartz Plates” , IEEE Transactions on Nuclear Science, Vol 55, Issue 2, , Apr 2008.
With these very nice comments from the editor and the refrees:
“The paper is very interesting and clearly proves that a solution exits for calorimeters in the SLHC era with similar light collection.”
“The authors are to be thanked for a very interesting piece of work”

7. 1st Paper : R&D Studies on Light Collection
We have tested/simulated different fiber geometries in the quartz plates, for their light collection uniformity and efficiency.
WaveLength Shifting (WLS) fiber, Bicron 91a, is embedded in the quartz plate. Quartz plates are wrapped with reflecting material of 95 % efficiency.
The Cerenkov photons reaching the PhotoMultiplierTube (PMT) are counted.
Cerenkov Photons are shown in green. Photons emitted by WLS process are shown in red.
At the test beams we compared the light collection efficiencies with that of original HE scintillators.

8. 2nd Paper : Quartz Plate Calorimeter Prototype - I
The first quartz plate calorimeter prototype (QPCAL - I) was built with WLS fibers, and was tested at CERN and Fermilab test beams.
Hadronic Resolution

9. What is missing on the 1st Phase?
- The WLS fibers used in QPCAL are BCF-12 by Saint Gobain (old Bicron) are not radiation hard.
The radiation hardness tests performed on BCF-12 shows that they are not very different than Kuraray 81 (current HE fibers).
The studies shows that BCF-12 can be more radiation hard with the availability of oxygen.

10. Engineering Options Second Phase of the R&D
1. How can we solve the fiber radiation problem?
a) Use engineering designs
b) Light enhancement tools (ZnO, PTP, etc.)
2. Radiation Damage Tests
a) On Quartz
b) On PTP
Engineering Options
Current BCF-12 WLS fiber is not very radiation hard, but it can still be used
*) We can engineer a system with fibers continuously fed thru a spool system. Iowa has
built the source drivers for all HCAL (Paul Debbins), we also have expertise on site;
Tom Schnell (University of Iowa Robotic Engineering).
We have shown that a set of straight (or a gentle bend) quartz plate grooves allow WLS fibers to be easily pulled out and replaced.
*) Different approach could be to use radiation hard quartz capillaries with pumped
WLS liquid. We have the expertise; B. Webb (Texas A & M), E. Norbeck (Iowa) and
D. Winn (Fairfield).
This has been studies at Fairfield. The liquid (benzyl alcohol + phenyl naphthalene) has an index of 1.6 but the attenuation length is still somewhat too short, possibly because of a too high WLS concentration.

11. Engineering Options
Current BCF-12 WLS fiber is very radiation hard, but it can still be used *) We can engineer a system with fibers continuously fed thru a spool system. Iowa has built the source drivers for all HCAL (Paul Debbins), we also have expertise on site; Tom Schnell (University of Iowa Robotic Engineering). We have shown that a set of straight (or a gentle bend) quartz plate grooves allow WLS fibers to be easily pulled out and replaced. *) Different approach could be to use radiation hard quartz capillaries with pumped WLS liquid. We have the expertise; B. Webb (Texas A & M), E. Norbeck (Iowa) and D. Winn (Fairfield). This has been studies at Fairfield. The liquid (benzyl alcohol + phenyl naphthalene) has an index of 1.6 but the attenuation length is still somewhat too short, possibly because of a too high WLS concentration.

12. Light Enhancement Tools
Proposed Solution
*) Eliminate the WLS fibers:
Increase the light yield with radiation hard scintillating/WLS materials and use a direct readout from the plate.
Questions… Questions …
*) What is out there to help us?
PTP (oTP, mTP, pQP), and/or ZnO can be used to enhance
the light production.
How to apply them to the plates? and what thickness?
Which one work better?
Which is more radiation hard?

13. Quartz Plates with PTP
At Fermilab Lab7, we have covered quartz plates with PTP by evaporation. We deposited 1.5, 2, 2.5, and 3 micron thickness of PTP.

14. Quartz Plates with PTP
PTP evaporation setup, and quartz plate holder

15. Quartz Plates with ZnO
We also cover quartz plates with ZnO (3% Ga doped), by RF sputtering.
0.3 micron and 1.5 micron.
We are currently working on 100 micron thick quartz plates, we’ve deposited ZnO on each
layer and bundle the plates together, for a radiation hard scintillating plate 
Fermilab Lab7, ZnO sputtering system and guns.

16. Test Beams for PTP and ZnO
We have opportunity to test our ZnO and
PTP covered plates, at CERN (Aug07), and
Fermilab MTest (Nov 07, and Feb 08).
Blue : Clean Quartz
Green : ZnO (0.3 micron)
Red : PTP (2 micron)

17. Test Beams for PTP and ZnO
Mips from plain quartz plate.
Mips from 0.3 micron thick ZnO (3% Ga) sputtered quartz plate.
Mips from PTP evaporated quartz plate.

18. Test Beams for PTP and ZnO
We evaporated PTP on quartz plates in IOWA
and tested them in MTest.
Different deposition amounts and variations
Were tested.

19. PTP Radiation Damage Tests
Sr-90  activated scintillation light output of the different pTP samples which
are  saturated in toluene.  
The toluene makes no measurable scintillation contribution.
Protons were done at CERN and Indiana Cyclotron.
The neutron data from Argonne.

20. What is learned from Phase II ?
The PTP and Ga:ZnO (4% Gallium doped) enhance the light production almost 4 times.
OTP, MTP, and PQP did not perform as well as these.
PTP is easier to apply on quartz, we have a functioning evaporation system in Iowa, works very well. We also had successful application with RTV. Uniform distribution is critical!!
ZnO can be applied by RF sputtering, we did this at Fermilab- LAB7. We got 0.3 micron, and 1.5 micron deposition samples. 0.3 micron yields better light output.
In light of these results we focused our efforts to Summer08 Cern Test Beam.

21. Cern Test Beam – Summer 2008
We have constructed and tested the QPCAL-II, with PTP deposited quartz layers.
The 20cmx20cmx5mm, GE-124 quartz plates are used.
2 μm PTP is evaporated on every quartz plate at Fermilab Lab 7.
The readout has been performed with Hamamatsu R7525 PMTs.
For hadronic configuration 7cm iron absorbers used between layers.
No WLS fiber! This is the second prototype “QPCAL-II”

22. Cern Test Beam – Summer 2008
We also have tested different thickness of ZnO and PTP deposited plates for mips.
Micro channel PMT prototype
Also HF PMT tests are performed by the same team.

23. Cern Test Beam – Summer 2008
The “new plate” with stack of seven 100 μm thick quartz plates, each sputtered ZnO on. This can give us a very radiation hard scintillating quartz plate. As a by product of our work .

24. QPCAL-II Hadronic Resolution
- We have taken data with
30, 50, 80, 130, 200, 250,
300, and 350 GeV Pion beam.
- Hadronic resolution is better
than 12% at E > 350 GeV.
*) At QPCAL-I the hadronic resoution was 18% at 300 GeV.

25. QPCAL-II Hadronic Response Linearity
Very linear response and
A nice signal distribution 

26. QPCAL-II EM Configuration
- After hadronic configuration the iron plates
between layers reduced to 2mm thickness
for Electron runs.
- We call this EM configuration.
- We took data with 50, 80, 100,
120, and 200 GeV electrons

27. QPCAL-II EM Configuration
We had very good EM resolution
As well, but at higher electron
Energies the signal started to
deviate.

28. QPCAL-II Muon Response
225 GeV Muon signal on QPCAL-II

29. Different PTP Thickness on Quartz
- The plate prepared in IOWA vacuum chambers performed
really well 
- Since we don’t have a thickness gauge we cannot tell the
thickness, but it has 1gr PTP deposited on 15cmx15cm quartz.
We did not see drastic variations between 2, 2.5, and 3 micron PTP deposited plates

30. 7 layer 700 micron ZnO plate
- We have deposited 0.2 micron ZnO (%4 Ga) to “100 micron” thick quartz plates.
- This sandwich structure with 0.7 mm total thickness is placed in an aluminum frame and tested for mips on this test beam for the first time.
- We got very promising results, for both pion and electron beams. We need to work on this technique to develop future “radiation hard scintillators”.

31. off-axis beam vs co-axis beam
The pyramids are positioned so the PMTs
Are not aligned with the beam.
When they are aligned with beam, we observe
Cerenkov form pmt window.

32. Results from Cern TB 08
We had very successful test beam, performed various tests at a very short time.
QPCAL-II with PTP deposited plates and performed better than QPCAL-I (withWLS fibers). With the obtained hadronic resolution of better than %13, we successfully finished the 2nd phase of our R&D.
As one of the many spinoffs of this
R&D , we showed than stacking very
Thin ZnO treated quartz plates, we can
Get “new rad-hard scintillators”.

33. Third Phase of the R&D Alternative Readout Options :
APD, SiPMT, PIN diode, Micro-channel PMT, MCP, MPPC
Which one is better? Wavelength response? Surface area?
Are they radiation hard?
Developing Radiation Hard Wavelength Shifing Fibers
Quartz fibers with ZnO covered core.
Sapphire fibers

34. New Readout Options We tested;
*) Hamamatsu S8141 APDs (CMS ECAL APDs).
The circuits have been build at Iowa. These APDs are known
to be radiation hard; NIM A504, (2003)
*) Hamamatsu APDs: S5343, and S K
*) PIN diodes; Hamamatsu S5973 and S
*) Si PMTs

35. New Readout Options SiPMT has lower noise level.
For all of these readout options we designed different
amplifier approaches:
50 Ohm amplifier.
Transimpedance amplifier.
Charge amplifier.
50 Ohm Amplifier circuit design.

36. New Readout Options
The speed of the readout is essential. The pulse width of the optical pulses from the
scintillator limits the selection of photodiode or
APD used. A bandwidth of 175 MHz is equivalent to a rise and fall time of 1.75 nsec.
Topology
Price
Speed (Rise time)
Input Equiv. Noise
Comments
Photodiode with 50 Ohm amplifier
Low
Fast (< 1 nsec)
~ 50 pW/√Hz
Simple circuitry
Photodiode with fast transimpedance amplifier
Moderate (< 3 nsec)
~ 10 pW/√Hz
APD with 50 Ohm amplifier
Moderate
Fast
~ 250 fW/√Hz
(Gain of 50)
Drift with temperature
High voltage
Moderate complexity for HV
APD gain from 25 to 150
Moderate (<3 nsec)
~ 50 fW/√Hz
Silicon PMT
~.1 fW/√Hz
Simple to moderate complexity

37. New Readout Options
We have tested ECAL APDs as a readout option. 2 APD connected to plain quartz
Plate yields almost 4 times less light than fiber+PMT combination.

38. So far what is learned from Phase III ?
Single APD or SiPMT is not enough to readout a plate. But 3-4 APD or SiPMT can do the job.
SiPMTs have less noise, higher gains, better match to PTP and ZnO emission λ.
As the surface area get bigger APDs get slower, we cannot go above 5mm x 5mm.
The PIN diodes are simply not good enough.
The ECAL APDs are claimed to be radiation hard
Feed the linear arrays of SiPMT or APD to the system, arranged as a strip of 5mm x cm long… engineering !!…
A cylindrical HPD, 5-6 mm in diameter, with a sequence of coaxial target diodes anodes on the axis, cm long, and a cylindrical photocathode.

39. Developing new technologies
We propose to develop a radiation hard readout option.
Microchannel PMT (Onel-Winn)
MCP-PMT ( Hamamatsu and Photonis)
MPPC (Multi Pixel Photon Counter)
We also propose to develop a radiation hard WLS fiber option.
Doped sapphire fibers.
Quartz fibers with ZnO sputtered on core.

40. Radiation hard readout option “Microchannel PMT”
*) Fairfield and Iowa have focused on revolutionizing photomultiplier technology through miniaturization coupled with the introduction of new materials technologies for more efficient photocathodes and high gain dynode structures. *) Miniaturization enables photomultipliers to be directly mounted on circuit boards or silicon for interfacing directly with readout circuits. *) Fast response time, high gain, small size, robust construction, power efficiency, wide bandwidth, radiation hardness, and low cost.

41. Radiation hard readout option “Microchannel PMT”
*) Photograph of a micromachined PMT in engineering prototype form.
*) The metal tabs for the dynode and focusing voltages, signal, cathode.
*) 8 stage device is assembled from micromachined dynodes which exhibits a gain of up to 2-4 per stage onsingle stage.
*) The total thickness < 5 mm.
*) 8x4 pixel micro-dynode array is shown
*) The layers are offset relative to each other to maximize secondary electron emission collisions.

42. Hamamatsu MPPCs Hamamatsu released a new product. Multi Pixel Photon
Counter, MPPC.
We purchased this unit, working on tests, but it is
simply an array of APDs. It is not the same thing with
our proposed “microchannel PMT”.

43. Ti:Sapphire looks promising
But not so fast !! Remember, there is NO quick solution to our problem 

44. Doped Sapphire !!
A. Alexandrovski et al.
Ti3+
Cr3+

45. Ag-Sapphire ??
A recent study shows that the Ag ions can be implanted into sapphire in the keV and MeV
energy regimes. The samples implanted at 3MeV shows a large absorption peak at the
wavelengths ranging from 390 to 450 nm when heated to temperatures higher than 800◦C.
Y. Imamura et al.

46. What can be done with sapphire?
Sapphire optical fibers are commercially available in standard lengths of 200 cm x 200 micron diameter. Cheaper stock fibners are 125 micron diameter x 125 cm long.  These fibers are of use in Ti:sapphire fiber lasers, and sensors.
A large variety of dopants are possible in sapphire, covering a large wavelength interval.
Under the right conditions, the Ti+4 ion (40 ppm) in heat treated sapphire absorbs in the UV and emits in the blue, with a time constant 5-7 ns. it is reasonably (50%-90% or more) efficient. At 1ppm the shift is at 415 nm - even at 1 ppm the fluorescnece is visible to the human eye. At 40 ppm it shifts to 480 nm. Fe2+ and Mg2+. Other Ti charge states and other dopants absorb in the UV-Blue and emit in the yellow and red.
We propose to investigate these and similar inorganic fibers, grown mainly for fiber lasers, but with dopants adjusted for fast fluorescence (rather than forbidden transistion population inversions), and to test the rad hardness.

47. What about treating quartz fibers?
Heterogenous nanomaterials Scintillating glass doped with nanocrystalline scintillators has also been shown to be a good shifter.
We propose
(i) testing radiation hardness and
(ii) to investigate doping quartz cores with nanocrystalline scintillators (ZnO:Ga and CdS:Cu). The temperatures involved are very reasonable.
Thin film fluorescent coatings on quartz cores nm UV has been shown to cause 5-10 ns fluorescence in MgF2, BaF2, ZnO:Ga. We propose coating rad-hard quartz fibers with a thin film, and then caldding with plastic or fluoride doped quartz. CVD deposition of Doped ZnO is now a commercial process, as it is used to make visible transparent conducting optical films as an alternative to indium tin oxide, as used in flat panel displays and solar cells.

48. Damage of HE scintillators
After 1.5·106 pb-1 integral luminosity
(10 years LHC + 1 year SLHC)
R (cm)
Z (cm)
After 5·105 pb-1 integral
luminosity (10 years LHC)
Tolerable level of the absorbtion dose for HCAL scintillators is order of 5·104 Gy (5 Mrad)
5 layers of HCAL megatiles will be affected severely

49. Thick Gas Electron Multiplier (THGEM)
The idea of the THGEM –
to obtain gas amplification
inside «GEM mesh»
Proposal from Russian Colleagues
Readout
Drift gap
Induction gap VD VU Vd VI V V
- 200 V
- 0 V
Schematic view of the THGEM chamber

50. The 10x10cm THGEMs were manufactured with standard PCB technology by precise drilling and Cu etching, out of double-face Cu-clad G-10 plate, of 0,4-0,8mm thickness
A gap of 0,1mm was kept between the rim of the drilled hole and the edge of the etched Cu pattern
Pitch, a=0,8mm
Rim, r=0,1mm
Hole, d=0,4mm
A microscope photograph of a THGEM

51. The pulse-height dependence on the event rate of the
THGEM for two different gains.
thickness=0,4mm, hole diameter d=0,3mm and pitch a=1,0mm
Effective gain of THGEM
thickness=0,4mm, hole diameter d=0,3mm and pitch a=0,7mm
THGEM
740 Torr

52. Issues of THGEM Production Technology
Different types of THGEM shape simulated using Maxwell (Sergey Vasilyev)
Distance along Y across THGEM detector (mm)
Electric field inside hole: ~40kV/cm
Electric field (V/m)
Electric field at the
age of the Rim:
~ kV/cm
Distance along R, on THGEM surface (mm) R Y
Rim
Hole
Induction :
3-5 Kv/cm
Drift:
1-2 Kv/cm
Multiplication
The shape of the rim have an impact on corona at the boundary of Cu clad
Technological issues to avoid sharpness at the age of the rim is under study

53. THGEM test pcb Boards were tested at HV = 2KV No sparks
100 mm
Double side G10 plate
Etched Cu diameter 0,5 mm
Cu foil
Drilled hole t
8 holes d=3.1mm
8 holes d=0.8mm
~10 mm
Rim around drilled holes
~ 5 mm
HV inputs from both sides of the
Cu plate
Boards were tested
at HV = 2KV
No sparks
1. Sensitive area 100 x 100 mm2
2. Material: double-face Cu clad G10 plate
Thickness: t = 0,4 ÷ 0,8 mm
Diameter of the hole: d = 0,4 mm
Pitch: p = 0,8 ÷ 1,2 mm
Rim around hole r = 0,1 mm

54. Participation in the HCAL beam test
The idea is to put the box of THGEMs: 4 planes ~30 x 30 cm separated by absorber (equivalent of 4 HCAL layers) in front of HCAL prototype on H2 beam
Goal – to measure energy resolution of HE with and without THGEM
2 options of R/O electrodes:
R/O pads 10x10cm
9 ch/plane x 4 planes = 36 R/O channels = 6 QIE boards
R/O pads 15x15cm
4 ch/plane x 4 planes = 16 R/O channels = 3 QIE boards
Total 36 R/O channels are needed = 6 QIE boards

55. Schedule – Quartz Plates
Purchase/Delivery of Quartz Plates: 4-6 months
Coating of the plates by PTP or ZnO(Ga): 4-6 months
Photodetector testing: 3 months
Final system assembly testing: 3 months
Total: 18 months

56. Back-up

57. Radiation Hard WLS fibers: Sapphire Fibers
Sapphire is a very radiation hard material and it can be brought into fiber form. But by itself
It has very little absorption and florescence.
Absorption in Sapphire can be provided by;
conduction to valence band in UV
multiphonon in mid-IR
native defects
vacancies, antisites, interstitials,
Impurities !!!!
e.g. transition metals: Cr, Ti, Fe, …
Tong et.al., Applied Optics, 39, 4, 495

58. Problems with Ti:Sapphire
There are some crystals used for lasers, but no fiber, yet.
The Ti:Sapphire has a luminescence lifetime of 3.2 microsec!! And looks like this is temperature dependent (Macalik et. al. Appl. Physc. B55, ) .
off “resonant” absorption significant
sum of several species can contribute to absorption at given l
Redox state important
e.g. a[Ti3+]  a[Ti4+]
annealing alters absorption without altering impurity concentrations
Impurities do not necessarily act independently
Al : Al :Ti3+ : Ti4+ : Al : Al  Al : Ti3+ : Al : Al : Ti4+ : Al
absorption spectra at high concentrations not always same as low