# Presentation: 158497

## SLHC tracking issues

***Regina Demina, ***
***University of Rochester***
**International Workshop on Future Hadron Colliders:****Physics, Detectors, Machines**

## Outline

**Accelerator upgrade stages**
**Requirements on tracking**
**Radiation hard R&D**
**Electronics issues**
**System integration issues**
**Summary**
**AI****=action item (to be addressed in future workshops)**

## LHC upgrade stages

**LHC performance:**
**7 TeV beam**
**Beam-beam tune spread 0.01**
**1.1 E11 p/bunch**
**L= 1E34 cm****-1**** s****-1**
**Phase 0: ****max performance w/o hardware changes to the LHC**
**Increase B to 9 T ******** E to 7.54 TeV**
**Increase bunch intensity to 1.7E11p/bunch ******** L=2.3E34**
- O. Brüning *et al.,* “LHC Luminosity and Energy Upgrade: a Feasibility Report”, LHC Project Report

## LHC upgrade stages

**Phase 1: ****max performance while keeping the LHC arcs**
** ********* = 0.5 ********0.25 m**
**Crossing angle 300 ********rad********425 ********rad (essential at decreased b* to minimize long range collisions)**
**Bunch intensity  at 1.7 E11 ******** L =3.3 E34 cm****-2**** s****-1**
**Bunch crossing interval 25 ********12.5 ns**
**Increased intensity and other modifications L=4.7 E34 cm****-2**** s****-1**
**Phase 2: ****max performance with major hardware changes to LHC**
**Modify injectors**
**Superconduct magnets for SPS (injection E********1TeV)**
**Mech and dynamic aperture changes ********x2 in L **
**L= 1.0 E35 cm****-2**** s****-1 ****by 2015**
**New superconducting dipoles E********14 TeV**** (a lot more R&D is needed) – not considered in this discussion**

## Tracking in SuperLHC1. Radiation damage

**Design luminosity =10xLHC**
**Running time = 1⁄2 LHC (5 years)**
**Radiation dose = 5xLHC**
**Inner layers of SiTrk (r=20cm) are expected to be operated at bias voltage 600V after 10 years of LHC**
**SuperLHC ******** 3kV (?!)**
**Need replacement**
**Need improved more rad hard technology**
**The goal is to maintain tracking and b-tagging performance**

## Tracking in SuperLHC 2. Granularity

**With collider energy and/or luminosity increase the emphasis shifts towards higher energy jets.**
**Energetic jets are more collimated ******** need higher granularity**
**A.I.**** Local occupancy is more critical. Need to understand for  typical jet E for objects at the threshold of sensitivity (e.g. use 7****th**** heavy quark M****Q ****production model)**

**R=20 cm**

**7% of tracks in 500 GeV jets **
**have merged hits **
**2.5% of tracks in 100 GeV jets**

## Possible detector configuration

**What to replace?**
**Most likely 100% of the tracking system**
**Lifetime (no relation to radiation damage) of Si systems so far <~3-4 years, LHC=8-10 years**
**Increase granularity**
**Electronics compatibility**
**To fix all the problems that are not known now**
**Scaling law radiation 1/r****2**
**R<20 cm – new technology **
**20<R<60 cm – pixels**
**R>60 – microstrips (with some technology pushing)**

## Directions in Tracking R&D

**Use of defect engineering silicon**
**E.g. DOFZ is now used for ATLAS pixels, possibility for CMS**
**3D and new biasing schemes**
**New sensor materials**
**Significant success with CVD diamonds**
**Cryogenic Silicon Tracker development**
**Lazarus effect – x10 increase in rad hardness**
**Monolithic pixel detectors**
**Sensor+readout on the same silicon substrate (no bump bonding)**

## Why now?

**CMS SiTrk detectors design time line**
**RD2 report – 1994**
**CMS technical proposal - 1994**
**RD20 report - 1995**
**RD48 report – 1997**
**Start construction phase 2003**
**Start data taking 2007 = 1994+13years**
**SuperLHC start data taking 2015**
**RD?? report 2015-13=2001 **
**RD50 is formed 10/02 to address the needs of Super LHC**

## RD50

**Approved by CERN 06/2002**
**52 institutions, 5 from US (Fermilab, Purdue, Rutgers, Syracuse, BNL)**
**Areas of research**
**Material engineering**
- Oxygenation, si carbite
**Device engineering**
- Pad, 3D, thin detectors
**Rad hard technologies used for LHC are not completely characterized **

## RD50

## Radiation damage – microscopic defects

## Radiation damage

**Leakage current grows with rad dose**
**P-type impurities concentration increases, sensor goes through n********p type inversion and then depletion voltage grows indefinitely**
**Annealing**
**Reverse annealing**

## Oxygen enriched silicon

**DOFZ (Diffusion Oxygenated Float Zone) O: 10****16****-10****17**** cm****-3**
**Introduced to HEP in 1999**
**Slows down V depl growth after type inversion**

**Reverse annealing delayed and saturated at high fluences**

## Device Engineering: 3D detectors

**Electrodes:**
**Narrow columns along detector thickness 3D**
**Diameter ~10 ********m, distance 50-100 ********m**
**Lower Vdepl**
**Thicker detector possible**
**Fast signal**

## CVD diamonds

**Good progress  lately Main issues charge collection distance reached 250 um **
**S/N = 8/1**
**Very radiation hard**
**Resolution improves (!) after 2E15  p/cm****-2**
**Pretty**

## Electronics issues

**0.25 um ******** 0.13 um**
**0.25 um might not be available on SLHC time scale or even worse only few vendors will be left **
**0.13 um – more rad hard**
**Tracker in L1 trigger**
**Binary? – ATLAS experience will tell**
**Power supplies (why do they always become an issue)**

**AI’s****:**
**Cost of 0.13 um development is very high**
**must managed cooperatively**
**Power consumption at 80 MHz**
**Signal level **
**At ~1V every welder in your neighborhood is your signal**

## System integration issues

**Large complex systems cannot be treated just as the sum of the parts**
**Installed in experiment detector systems exhibit features not present in laboratory testing**
**Commissioning is becoming a lengthy process 1-1.5 years**
**Why we are never able to get to b-tagging efficiency seen in Monte Carlo?**

## Examples of “integration issues”

**SuSy will jump at you after 2-3 weeks of LHC data taking**
***Not the first two weeks***

**Susy?**
**No, calorimeter noise**

**Silicon tracker (WSMT) ******** calorimeter “cross talk”**
**Welders**

**DØ**

## Examples of “integration issues”

**CDF L00 – signal carried by analogue cables **
**Readout the whole L00**
**Fit pedestals with Chebyshev polynomials**
**Another interesting story**
**Resonance Lorentz force ******** wirebond breaks**

## AI on integration

**A lot of experience gained by Tevatron **
**on integration and commissioning of large detector systems**
**Statistics of failure modes (e.g. 12% of a system lot due to poor cable connection)**
**grounding**
** ****Documentation**
** ****System integration is a worthy R&D project**

## Summary

**LHC upgrades will deliver x10 in L and possibly x2 in energy**
**Most likely entire tracking systems of both high Pt experiments will have to be replaced**
**Requirements to tracking upgrades**
**Radiation hardness**
**Higher granularity**
**Fast response**
**R&D program has started:**
**RD50 – silicon detectors**
**RD42 – good progress with CVD diamonds**
**Electronics: 0.25 ******** 0.13 um transition **
**System integration must be given high priority**

## Action Items

**Understand local occupancy for  typical jet E for objects at the threshold of sensitivity (e.g. use 7****th**** heavy quark M****Q ****production model)**
**Electronics: **
**Cost of 0.13 um submissions **
**Power consumption**
**Signal and noise levels**
**Integration**
**Documentation of Tevatron experience**
**R&D task**