1. 1 1 David Hitlin May 17, 2002 David Hitlin May 17, 2002 FPCP FPCP

2. 2 2 Is there a 10 36 future? This talk will not discuss in detail the physics case for a 10 36 machine This talk will not discuss in detail the physics case for a 10 36 machine The case is strong; we are working on refining the arguments The case is strong; we are working on refining the arguments CP violation in B decay is likely to remain the centerpiece CP violation in B decay is likely to remain the centerpiece Precision CP studies and other measurements related to achieving the ultimate sensitivity in consistency tests of the Standard Model Precision CP studies and other measurements related to achieving the ultimate sensitivity in consistency tests of the Standard Model Measurements of CP -violating asymmetries in rare decays, such as B  K*l + l - as a sensitive new probe of SUSY effects Measurements of CP -violating asymmetries in rare decays, such as B  K*l + l - as a sensitive new probe of SUSY effects Complementarity with hadron machines Complementarity with hadron machines Rather, the talk is aimed at exploring an upgrade path from the current B A B AR detector to a new Super B A B AR detector capable of coping with 10 36 Rather, the talk is aimed at exploring an upgrade path from the current B A B AR detector to a new Super B A B AR detector capable of coping with 10 36 Presumably a similar case could be made for an upgraded Belle Presumably a similar case could be made for an upgraded Belle

3. 3 3 With 10 ab -1, the Gronau-Wyler construction can place a stringent limit on penguin amplitudes Roodman Requires measurement of tagged and decay branching fractions Isolating the penguin contribution in Roodman

4. 4 4 SLAC-PUB-8970 At 10 36, e + e - is complementary to LHCb/BTeV/ATLAS/CMS

5. 5 5 Bartl, Gajdosik, Lunghi, Masiero, Porod, Stremnitzer and Vives, hep:ph/0103324 MSSM: CP asymmetry in b  s 

6. 6 6 The Snowmass Strawman design was developed as an existence proof that a 10 36 detector could be built at all The Snowmass Strawman design was developed as an existence proof that a 10 36 detector could be built at all Main concerns Main concerns Radiation dose Radiation dose Machine-related backgrounds Machine-related backgrounds synchrotron radiation synchrotron radiation particle backgrounds, due primarily to continuous injection particle backgrounds, due primarily to continuous injection Physics backgrounds – hadronic split-offs, ….. Physics backgrounds – hadronic split-offs, ….. The 10 36 environment G. Eigen

7. 7 7 We concluded that such a detector could be built

8. 8 8 A potential upgrade path from B A B AR to Super B A B AR 1.Flux return and IFR upgraded à la MINOS 2.Remove SVT, DCH, EMC, DIRC 3.New EMC – liquid Xe 4.New tracker – Two inner pixel layers Seven(?) thin double-sided Si-strip arch layers 5.New DIRC(s) with compact readout DIRC

9. 9 9 The power bill is a function of the energy asymmetry J. Seeman

10. 10 10 Studies of the energy asymmetry have been updated S. Wagner Normalized luminosity degradation factor

11. 11 11 Tracking and Particle ID Tracking Tracking Snowmass concept of two pixel layers + seven double-sided strip layers is well-suited to the upgrade Snowmass concept of two pixel layers + seven double-sided strip layers is well-suited to the upgrade B=1.5 T vs. 3 T for Snowmass design B=1.5 T vs. 3 T for Snowmass design R outer = 75 cm vs. 45 cm R outer = 75 cm vs. 45 cm Momentum resolution improved by ~40%, but silicon area is greater Momentum resolution improved by ~40%, but silicon area is greater Particle ID Particle ID Barrel Barrel New non-SOB DIRC is under development New non-SOB DIRC is under development Quartz is sufficiently radiation hard Quartz is sufficiently radiation hard Need pixel readout Need pixel readout Endcap Endcap Requires single photoelectron readout in a magnetic field Requires single photoelectron readout in a magnetic field No DIRC design yet exists No DIRC design yet exists Aerogel would work Aerogel would work

12. 12 12 EMC and Instrumented Flux Return EMC requirements EMC requirements Fast response Fast response Radiation Hardness Radiation Hardness Excellent energy and position resolution Excellent energy and position resolution Longitudinal segmentation for best possible p /e separation Longitudinal segmentation for best possible p /e separation Minimal interruption in barrel/endcap region Minimal interruption in barrel/endcap region Can be met by a scintillating liquid xenon calorimeter IFR requirements IFR requirements High rate capability High rate capability Good time resolution Good time resolution Stable response Stable response Can be met by a MINOS-type scintillating strip design

13. 13 13 Comparison of CsI(Tl), LSO, Liquid Xe CsI(Tl)LSOLXe Atomic number Z54 effective65 effective54 Atomic weight A131 Density (g/cc)4.537.402.953 Radiation length (cm)1.851.142.87 Moli è re radius (cm) 3.82.35.71 l scint (nm) 550420175 t scint (ns) 680, 3340474.2, 22, 45 Light yield (photons/MeV)56,000 (64:36)27,00075,000 Refractive index1.81.821.57 Liquid/gas density ratio519 Boiling point at 1 atmosphere (K) 165 Radiation hardness (Mrad)0.01100- Cost/cc3.2>7 (50 ???)2.5

14. 14 14 Using the 175nm light from liquid xenon Xe scintillation light has been measured with several techniques Xe scintillation light has been measured with several techniques Multi-alkali PMT Multi-alkali PMT CsI photocathodes CsI photocathodes Wavelength-shifting coatings Wavelength-shifting coatings APD’s in LXe at ~165K APD’s in LXe at ~165K

15. 15 15 Conceptual design of a scintillating LXe EMC for Super B A B AR The key idea is to absorb the 175 nm scintillation light in wavelength shifting fibers, read out by a photosensor, such as a pixelated APD, that works at cryogenic temperatures in a magnetic field The key idea is to absorb the 175 nm scintillation light in wavelength shifting fibers, read out by a photosensor, such as a pixelated APD, that works at cryogenic temperatures in a magnetic field Shift from UV to visible on the cell walls and then shift again in a fiber Shift from UV to visible on the cell walls and then shift again in a fiber The volume of liquid xenon required is ~10 m 3  30 tons (1 year’s production) The volume of liquid xenon required is ~10 m 3  30 tons (1 year’s production) Current world price of LXe is ~ $2,500/liter Current world price of LXe is ~ $2,500/liter LXe light yield = 75,000 photons/MeV LXe light yield = 75,000 photons/MeV Estimated photoelectron yield is hundreds of photoelectrons/MeV Estimated photoelectron yield is hundreds of photoelectrons/MeV Stochastic term in energy resolution <1% Stochastic term in energy resolution <1% Energy resolution will be determined by Fano factor, insensitive material, shower leakage, albedo, …….. Energy resolution will be determined by Fano factor, insensitive material, shower leakage, albedo, …….. Spatial resolution is determined by number of sensors Spatial resolution is determined by number of sensors s /E E (GeV)

16. 16 16 Example EGS showers in liquid xenon 100 MeV 200 MeV 300 MeV 500 MeV 750 MeV 14 X 0 1000 MeV Thanks to Ralph Nelson and Ray Cowan

17. 17 17 Hexagonal cell structure built of eptfe or aluminized mylar Non-load bearing hex structure Non-load bearing hex structure TPB-coated eptfe compartments TPB-coated eptfe compartments Reflectivity for shifted light Reflectivity for shifted light is 95% for sufficient thickness is 95% for sufficient thickness Non-sensitive material Non-sensitive material Mylar 5 mils = 4x10 -4 X 0 Mylar 5 mils = 4x10 -4 X 0 eptfe 0.5 mm = 2x10 -3 X 0 eptfe 0.5 mm = 2x10 -3 X 0 Fiber 1 mm = 2x10 -3 X 0 Fiber 1 mm = 2x10 -3 X 0

18. 18 18 Unit cell of the LXe EMC Hexagonal cells of ~ 1 Molière radius in transverse dimension are formed from thin quadraphenyl butadiene (TPB)-coated eptfe sheets Hexagonal cells of ~ 1 Molière radius in transverse dimension are formed from thin quadraphenyl butadiene (TPB)-coated eptfe sheets Cells are not load-bearing, thus thin Cells are not load-bearing, thus thin Longitudinal segmentation is provided by TPB-coated optical separators, with WLS fibers sensitive only in a particular segment Longitudinal segmentation is provided by TPB-coated optical separators, with WLS fibers sensitive only in a particular segment Three segments is probably optimal Three segments is probably optimal 1. Massless gap – ascertain whether there was an interaction in material in front of the EMC Two larger segments, with division near shower max 2, Two larger segments, with division near shower max Fibers are read out by a pixelized APD, located in the LXe volume Fibers are read out by a pixelized APD, located in the LXe volume Clear fibers between coil segment and APD Clear fibers between coil segment and APD Redundant readout is simple and inexpensive Redundant readout is simple and inexpensive All readout at rear, minimizing nuclear counter effect All readout at rear, minimizing nuclear counter effect

19. 19 19 How do we detect the shifted light from TPB? - continued TPB emission Y11 Y8 Y8,Y11 emission Y8,Y11 absorption RMD pixelized APB QE LXe scintillation External QE of TPB # photons emitted into 2 p # photons incident vs incident wavelength (Lally, et al.) is high Capture efficiency of Y11 ~5.5-7% ~80% ~80%

20. 20 20 WLS fibers and APD readout Does the light get into the fibers? Does the light get into the fibers? Yes: n polystyrene =1.59 n LXe =1.57 Yes: n polystyrene =1.59 n LXe =1.57 Conversion efficiency of WLS: Conversion efficiency of WLS: Conversion ~80-90 % in Y11 Conversion ~80-90 % in Y11 Capture efficiency of fiber Capture efficiency of fiber Round Round Single clad 3.1% Single clad 3.1% Multi clad 5.4% Multi clad 5.4% Square Square Single clad 4.2% Single clad 4.2% Multi clad 7.3% ??? Multi clad 7.3% ??? Square fiber has more surface area and is a better match to square pixel Square fiber has more surface area and is a better match to square pixel transmission coefficient close to 1 1 mm 30 m m polystyrene PMMA fluorinated PMMA

21. 21 21 Candidate readout device RMD pixelized APD RMD pixelized APD 8x8 array with 1mm pixels MINOS Far Detector 1 mm WLS fibers

22. 22 22 There is an optimal helix pitch Absorption length of Y11 fiber dictates the pitch Absorption length of Y11 fiber dictates the pitch For a single fiber, read out at both ends: For a single fiber, read out at both ends: By varying the pitch, light collection efficiency can be made uniform By varying the pitch, light collection efficiency can be made uniform Pitch (cm) Efficiency (%) l abs (cm) 500 400 300 200 100 5X 0 section Pitch (cm) Efficiency (%) l abs (cm) 500 400 300 200 100 9X 0 section 1.2 1.0 0.8 0.6 0.4 0.2 0 1.2 1.0 0.8 0.6 0.4 0.2 0

23. 23 23 A working device trumps a calculation Radiative decay of the metastable molecule in liquid helium D. N. McKinsey, C. R. Brome, J. S. Butterworth, S. N. Dzhosyuk, P. R. Huffman, C. E. H. Mattoni, and J. M. Doyle Department of Physics, Harvard University, Cambridge, Massachusetts 02138 R. Golub and K. Habicht Hahn-Meitner Institut, Berlin-Wannsee, Germany PHYS. REV. A59, 200, JANUARY 1999 Scintillation light from liquid helium has been observed using a technique much like that proposed here Scintillation light from liquid helium has been observed using a technique much like that proposed here LHe scintillates at LHe scintillates at TPB (tetraphenyl butadiene) (0.2mg/cm 2 ) evaporated on TPB (tetraphenyl butadiene) (0.2mg/cm 2 ) evaporated on 1.6mm Gore-tex (eptfe) walls ~20cm length x 4.1cm diameter 1.6mm Gore-tex (eptfe) walls ~20cm length x 4.1cm diameter + 2 coiled Kuraray Y11 fibers (~430  490nm) @ 6mm pitch + 2 coiled Kuraray Y11 fibers (~430  490nm) @ 6mm pitch Hamamatsu R943-02 PMT Hamamatsu R943-02 PMT with 13% QE at 500 nm with 13% QE at 500 nm Estimated efficiency 0.04% to 0.14% Estimated efficiency 0.04% to 0.14% 80nm

24. 24 24 The future of e + e - - based heavy flavor physics The physics case for a data sample of 50 ab -1 is there The physics case for a data sample of 50 ab -1 is there A focused argument must still be crafted A focused argument must still be crafted It appears that a 10 36 B Factory can be built It appears that a 10 36 B Factory can be built It is likely that it will have bg =0.5 or less It is likely that it will have bg =0.5 or less There is an upgrade path from B A B AR to Super B A B AR There is an upgrade path from B A B AR to Super B A B AR An LXe-based upgrade of B A B AR may be a viable approach An LXe-based upgrade of B A B AR may be a viable approach LXe is likely just one of several alternative approaches LXe is likely just one of several alternative approaches Alternative technologies also likely exist for tracking, muon ID, PID Alternative technologies also likely exist for tracking, muon ID, PID

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