ATLAS Inner Detector Upgrade

Transcription

1 ATLAS Inner Detector Upgrade 11th Topical Seminar on Innovative Particle and Radiation Detectors Siena, Italy 3 October 2008 Paul Dervan, Liverpool University On behave of the: ATLAS High Luminosity Upgrade Group 1

2 Contents Introduction Physics motivation for upgrade Implication on tracking detector design Current design Summary 2

3 ATLAS Inner Detector Upgrade To keep ATLAS running more than 10 years the inner tracker has to be replaced (Current tracker designed to survive up to 730 fb-1 10Mrad in strip detectors) For the luminosity-upgrade (SLHC) the new tracker will have to cope with >3000 fb-1 much higher occupancy levels much higher dose rates 1016neq/cm2 pixel b-layer neq/cm2 middle layers neq/cm2 outer layers For a new tracker by 2015, major international R&D programme already underway. (Current ATLAS Inner Detector TDR CERN/LHCC/97-16 is now 11 years old) 3

4 LHC Machine Upgrade Big challenge to increase luminosity by a factor of 10 Two scenarios currently being considered L 1) Improve beam focusing small β* 25 ns bunch crossing machine magnets inside ATLAS 2) Increase beam currents More demanding on machine 50 ns bunch crossing No machine magnets inside ATLAS parameter symbol protons per bunch Nb [1011] bunch spacing t [ns] beam current I [A] longitudinal profile N p2 β * 25 ns, small β* 50 ns, long Gauss Flat rms bunch length σz [cm] beta* at IP1&5 β [m] full crossing angle θc [µrad] peak luminosity L [1034cm-2s-1] peak events per crossing initial lumi lifetime effective luminosity (Tturnaround=5h) τl [h] L [1034cm-s-1]

5 Physics Motivation for Luminosity Upgrade LHC can extend the LHC mass reach by 30% Increase/consolidate LHC discovery potential at the TeV scale Can improve on precision measurements: SM parameters and Higgs couplings Parameter measurement of New Physics if discovered (e.g. SUSY) Increase sensitivity to rare processes/rare decay modes Example of improved mass reach - taking into account CMS acceptance and e/µ reconstruction efficiency and pile-up noise. Eur.Phys.J.C39(2005)293 5

6 New SLHC Layout Implications: Radiation Dose Design fluences for sensors (includes 2x safety factor) Innermost Pixel Layer: neq/cm2 Outer Pixel Layers: 3* 1015 neq/cm2 Short strips: neq/cm2 Long strips: neq/cm2 Issues of thermal management and shot noise. Silicon looks to need to be at ~ -25oC (depending on details of module design). High levels of activation will require careful consideration for access and maintenance. Issues of coolant temperature, module design, sensor geometry, radiation length, etc etc all heavily interdependent. Quarter slice through ATLAS inner tracker Region, with 5cm moderator lining calorimeters. Fluences obtained using FLUKA2006, assuming an integrated luminosity of 3000fb-1. I. Dawson (Sheffield) 6

7 New SLHC Layout Implications: Occupancy Occupancy should be less than two percent Inner micro-strip layers have to be 2.4 cm long Outer micro-strip layers are 9.6 cm Short and Long Strip Occupancy J. Tseng (Oxford) 7

8 New SLHC Layout Pixels: r=5cm, 9cm, 18cm, 27cm z=±40cm Short (2.4 cm) µ-strips (stereo layers): r=38cm, 49cm, 60cm z=±120cm Long (9.6 cm) µ-strips (stereo layers): r=75cm, 95cm z=±120cm Including disks this leads to: Pixels: 5 m2, ~300,000,000 channels Short strips: 60 m2, ~28,000,000 channels 8 Long strips: 100 m2, ~15,000,000 channels

9 HPK n-in-p Sensor Mask Layout Strip segments 4 rows of 2.4 cm strips (each row 1280 channels) Dimension Full square Wafer 150 mm p-type FZ(100) 138 mm dia. usable 320 µm thick Axial strips 74.5 µm pitch Stereo strips 40 mrad 71.5 µm pitch Bond pads location accommodating mm distances n-strip isolation (still under investigation) P-stop Spray 9.75cm 9.75cm Y. Unno (KEK) 9

10 Fluence in SLHC Layout satlas Fluences for 3000fb-1 1.E+17 All: RTF Formula n (5cm poly) pion proton Long Strips Fluence neq/cm 2 1.E+16 Long and short strips damage largely due to neutrons 1.E+15 1.E+14 1.E+13 Short Strips 1.E+12 0 Pixels Mix of neutrons, protons, pions depending on radius R Radius R [cm] Pixels damage due to neutrons and pions ATLAS Radiation Taskforce Need to study response to both neutral (neutrons) and charged (proton) particle irradiations 10

11 Irradiated Microstrip CCE(V) Microstrips Pixels Microstrips 500 V Pixels 800 V n-in-p FZ planar technology candidate for all layers 12ke of charge is collected at 500V at the higher qualification fluence for the innermost microstrip region of the SCT upgrade, much higher than the 8ke that provide an estimated S/N of 10 for the anticipated geometry. Liverpool group 11

12 Prototype SLHC Hybrid Services coming in at both ends of the hybrid Hybrid defined as a single finger Composed of 2 columns of 10xABCn i.e. 20 front-end ASICs Token By-pass MCC I/O Data Link 1 Common TTC (serving 20x ABCn) DCS, Power, HV Data Link 0 MCC I/O Digital I/O A. Greenall (Liverpool) Readout architecture Common TTC (Clk, Com, L1, Data Clk and Reset) routed to 20 ABCn No redundant TTC on hybrid (nowhere to route!) 1 x data Link per column i.e. 2 data links per hybrid All I/O provided for MCC readout at each end of a column Will now have 4 data links per hybrid (shown in red) This can be by-passed (by wire-bonds) i.e. only maintain 2 data links 12

13 Stave Concept The stave concept has hybrids glued to sensors glued to cold support A first prototype version based on the CDF run-iib concept but using ATLAS ASICs has been reported at conference A 6-chip wide version (Stave-07) uses short p-in-n sensors and incorporates many of the final proposed, mechanical, thermal, electrical, serial powering and read-out features. The first prototype staves are undergoing evaluation Stave core, BeO hybrid design, electrical bus, serial powering and several full modules implemented 10 chip wide version next C. Haber (LBL) 13

14 KEK Superframe Concept Build individual double sided modules Insert modules into a Superframe Supermodule Y. Unno (KEK)

15 Thermal FEA of module Cooling P.Sutcliffe (Liverpool) 1W/Sensor 0.3W/Chip Si Temp: -25C Temp Gradient over Si: 1.17C 15

16 End Insertion of supermodules 1) Ready for next super module 2) Align supermodule with track 3) Slide in place & lock down I. Wilmut (RAL)

17 End Stave Services University of Geneva and LAPP 17

18 Summary The tracker of ATLAS will have to be replaced in 2015 The LHC will increase it s luminosity by a factor of 10 The inner silicon strips will have to be shorter than the current design to deal with the increased occupancy Lots or R&D has already been carried out and ideas are converging 18

19 Backup

20 Sensors n-in-p technology developed at Liverpool Comparison of measured collected charge on different radiation-hard materials and devices (M. Bruzzi, H. F.-W. Sadrozinski, A. Seiden, NIM A 579 (2007) ) p F Z S i µ m ; 2 5 n s ; -3 0 C [1 ] p - M C z S i µ m ; µ s ; C [2 ] n E P I S i 7 5 µ m ; 2 5 n s ; C [3 ] n E P I S i µ m ; 2 5 n s ; -3 0 C [3 ] s C V D D i a m µ m ; 2 5 n s ; C [4 ] p C V D D ia m µ m ; 2 5 n s ; C [ 4 ] # e le c tr o n s Signal # e(electrons) le c tr o n s n E P I S ic 5 5 µ m ; 2. 5 µ s ; C [ 5 ] D F Z S i µ m [6 ] Signal vs Dose Latest n-in-p data 0 from Liverpool (1000V) Micron e n cltd e [c m ] SemiconductorF luuk M e V n flu e n c e [ c m ] 16 20