# Presentation: 011132

## Presentation at theAspen Meeting of the PAC

**John Womersley**
**On behalf of the D****Ø**** Collaboration**
- June 2003

## Question 1

*	**What is currently your best understanding of how the performance of the silicon detector will diminish with increasing integrated luminosity? What is the impact of this degradation in performance on the most important physics analyses? Which physics topics suffer the most from this effect and which least?**** ***
**Radiation damage lifetime e****stimated from**
**locations and types of detectors installed in DØ**
**measurement-based knowledge of the phenomenology of radiation damage**
**actual measured doses received**
**expect the lifetime will be limited by micro-discharge breakdown of the junction in the Micron detectors in the inner barrels.  **
**begins to occur at bias of ~ 150 V; all channels fail at ~200 V   **
**will start to lose significant numbers of channels at an integrated luminosity of 3.6 ******** 1.8 fb****-1**** **
**all of the channels on the inner layer will be dead by 4.9 ******** 2.5 fb****-1****. **
**These uncertainties reflect how well we can estimate the micro-discharge formation and dose accumulation.**

## Longevity of the detector
Fraction of disabled ladders was 6% in 2001 and is ~ 12% now
No reason to believe this is anything to do with radiation damage
We have no idea how to extrapolate this to the future

**Fraction of disabled ladders was 6% in 2001 and is ~ 12% now**
**No reason to believe this is anything to do with radiation damage**
**We have no idea how to extrapolate this to the future**

**% ladders**
**disabled**

## Impact of degradation

**We know that loss of silicon layers will impact b-tagging:**
**Lower efficiencies**
**Also degrades precise tracking and primary vertex identification capability**
**Hence worse missing E****T**** and jet resolution**

**Run IIb detector**

## Physics affected

**Physics which requires multiple b-tags is affected most:**
**Top quark physics, including precision mass measurements**
**Standard Model Higgs Searches**
**Supersymmetry searches involving light stop and sbottom **
**Supersymmetry searches involving cascade decays of squarks or gluinos to heavy flavor**
**Supersymmetric Higgs searches in 4b and bb******** modes**
**Technicolor searches**
**The entire B-physics program**
**Flagship physics of the Tevatron**

## The silicon detector is an integral part of the DØ tracking system
Needed for pattern recognition and track sagitta measurements

Almost all physics is affected by loss of precision tracking and primary vertex identification:
W mass and electroweak physics
Supersymmetry searches in trileptons
Supersymmetry searches with taus
Extra dimensions
Jets and missing ET

**Needed for pattern recognition and track sagitta measurements**
**Almost all physics is affected by loss of precision tracking and primary vertex identification:**
**W mass and electroweak physics**
**Supersymmetry searches in trileptons**
**Supersymmetry searches with taus**
**Extra dimensions**
**Jets and missing E****T**

## Question 2

*How much time is needed to install and commission the new silicon detectors?** *
**We have put together a fully resource loaded plan for**
**Opening the detector**
**Removal of the old silicon**
**Installation of the new silicon **
**4.5 months**
**Cabling and Technical commissioning **
**10 weeks (1.5 shifts, 2 teams of 2 people per shift)**
**Online software (downloads, calibrations, unpacking, monitoring...)**
**1.5 months (in parallel with above)**

## The plan also integrates the installation of the trigger upgrades
Total shutdown duration is 7 months
Experts feel this is conservative

**Total shutdown duration is 7 months**
**Experts feel this is conservative**

## Question 3

*	**At what time after the end of the shutdown period would the full experiment be able to record physics-quality data with good efficiency?** *
**We know we have to come up quickly**
**We are putting a detailed beam commissioning plan together**
**Silicon**
**In Run II we had problems with**
**LV power supplies – now moved outside the hall**
**Downstream electronics – now fixed, will not change**
**Interface boards – hence heavy emphasis on technical commissioning before close-up**
**Successful as-built alignment procedure allowed physics quality data to be taken rapidly in Run IIa**

## Trigger
Will use splitter cards to allow parasitic commissioning  of calorimeter trigger before the long shutdown
Calorimeter trigger calibration requires ~ 1 week of beam time +  4 weeks analysis after shutdown

For the silicon and trigger upgrades together, we estimate that 3 months of commissioning time with beam will be needed

**Will use splitter cards to allow parasitic commissioning  of calorimeter trigger before the long shutdown**
**Calorimeter trigger calibration requires ~ 1 week of beam time +  4 weeks analysis after shutdown**
**For the silicon and trigger upgrades together, we estimate that 3 months of commissioning time with beam will be needed**

## Question 4

*	**What strategy would the collaboration prefer for the detector upgrades and what are the most important drivers of this position?  What should be the conditions for beginning the extended shutdown to install the silicon detector upgrades?  What is the minimum time of operation after the shutdown needed to justify installing the silicon detector?*
**I shall defer answering the first part until the end of this presentation**

## Conditions to begin shutdown

**We cannot state hard-and-fast conditions for beginning the silicon installation shutdown.  **
**The decision will be a complicated optimization exercise including a good measure of gut feeling.  **
**We will need to consider:**
**The state of readiness of the detector upgrades (both DØ and CDF)**
**The performance of the existing tracking system including **
**radiation damage (if any)**
**further component losses (if any)**
**pattern recognition performance in the high occupancy environment**
**Accelerator performance up to that date and projections for the following two years**
**The state of the LHC accelerator and detectors at that time**
**Any discoveries or hints of new physics in the Run II data.**** **

## How long to run?

**It is important to note that the upgraded DØ silicon detector offers increased performance over the current device.  **
**six layers rather than four **
**better pattern recognition at high occupancy**
**inner layers are closer to the beampipe**
**Significantly improved b-tagging**
**It is not a spare part, it is a higher performance detector.   **
**A very rough figure of merit is that the double b-tagging efficiency with the new detector is 1.7 times higher than the existing device, even in the absence of radiation damage to the latter**
**Full GEANT simulation of ZH + 7.5 minbias events**
**We believe that, after roughly a year of downtime, a physics running period also of a year or so at high luminosity would justify installing the new detector. **

## Question 5

*	**Please review the motivation for each of the non-silicon detector upgrades and comment on any substantial changes that might occur due to the new luminosity profiles.*
**For DO, the non-silicon upgrades are:**
**Level 1 trigger**
**Calorimeter clustering at level 1**
**Calorimeter-track matching**
**Fiber tracker trigger upgrade**
**Level 2 trigger**
**Silicon Track Trigger upgrade**
**Beta processors**
**Level 3 **
**Processor upgrades**

## These upgrades were designed to handle luminosity of  21032 cm-2s-1 with a bunch spacing of 396 ns, maintaining enough headroom to handle peak luminosities up to 41032 cm-2s-1. 
The motivation is to keep the L1 accept rate under control and to maintain rejection at L2 and L3

The upper curve of the new luminosity profile corresponds to instantaneous luminosity reaching 21032 cm-2s-1 some time in FY06, and approaching 31032 cm-2s-1 in FY08.

The lower curve exceeds 11032cm-2s-1 in FY07, and eventually reaches about 1.71032cm-2s-1.  

	All of the non-silicon upgrades are still required* 

* Part of the STT upgrade is still needed even without the silicon upgrade

**The motivation is to keep the L1 accept rate under control and to maintain rejection at L2 and L3**
**The upper curve of the new luminosity profile corresponds to instantaneous luminosity reaching 2********10****32**** cm****-2****s****-1**** some time in FY06, and approaching 3********10****32**** cm****-2****s****-1**** in FY08.**
**The lower curve exceeds 1********10****32****cm****-2****s****-1**** in FY07, and eventually reaches about 1.7********10****32****cm****-2****s****-1****.  **
**	****All of the non-silicon upgrades are still required* **
*** Part of the STT upgrade is still needed even without the silicon upgrade**

## Ancillary Questions

## Slide 17

## Z   with 104pb1 of 2002-2003 data

**Z ******** ******************** ****with 104pb********1**** of 2002-2003 data**

## Upgrade Status

**The detector upgrades are proceeding well**
**Latest version of the SVX4 chip looks good**
**We have prototyped all components **
**No major technical problems remain**
**We have started to place the final production orders for various components**
**Roughly $8M has been obligated so far of $28.6M TPC (45% cont)**
**$2.5M “in kind” including $2M from NSF**
**Available contingency can take us to roughly January 04**

## The collaboration

**We are continuing to add members**
**At next week’s Institutional Board Meeting we will consider applications from Clermont-Ferrand and from Simon Fraser University**
**We have expressions of interest from two more institutions**
**For the Upgrade Lehman Review, we obtained MOU’s from 75 of 76 institutions**
**All are committed to Run IIb or are developing proposals for continued participation.**
**We have commitments of sufficient physicist effort for the Run IIb detector projects.  **
**Summed person-years meet or exceed requirements extracted from the resource-loaded schedule for both silicon tracker and trigger/DAQ/Online projects.**** **
**For the operations phase, we understand that we need to transition to a “LEP-like” mode of running**
**Preliminary estimate: we need ~ 80 FTE’s to operate the experiment, its software and computing**

## Physics issues beyond the Higgs

| One Experiment | 2 fb-1 | 5 fb-1 | 10 fb-1 |
| --- | --- | --- | --- |
| # high pT jets > 400 GeV | 1300 | 3300 | 6600 |
| Gluino mass | 400 GeV | ~ 450 GeV? | ~ 500 GeV? |
| Trileptons m1/2 reachtan  = 5, m0 smalltan  = 5, m0 largetan  = 35, m0 large |  m1/2 ~ 220 GeV-- m1/2 ~ 120 GeV |  m1/2 ~  235 GeV m1/2 ~ 140 GeV m1/2 ~ 145 GeV |  m1/2 ~ 250 GeV m1/2 ~ 160 GeV m1/2 ~ 170 GeV |
| GMSB  + METchargino mass | 325 GeV | 345 GeV | 370 GeV |
| SUSY Higgs + bbreach in tan  for mA = 150 GeV | tan  > 45 | tan  > 35 | tan  > 27 |
| Topcolor Z tt  | mass < 580 GeV | 640 GeV | 720 GeV |
| Z dijets | mass < 560 GeV | 610 GeV | 650 GeV |
| Z dileptons | mass < 1 TeV | 1.15 TeV | 1.3 TeV |

**And don’t forget SUSY searches/exclusion using the h**

## What counts for all of the above is luminosity  efficiency

| One experiment | 2 fb-1 | 5 fb-1 | 10 fb-1 |
| --- | --- | --- | --- |
| # top events 3 jets + 1b-tag4 jets + 2b-tags | 1000240 | 2500600 | 50001200 |
| Top mass: Lepton + jetsDileptons | 
2.7 GeV2.8 GeV | 
2.2 GeV2.2 GeV | 
1.6 GeV1.6 GeV |
| Single topcross section (s / t)|Vtb| (s / t channel) | 21% / 12%12% / 10% | 13% / 8%8% / 9% | 9% / 5%6% / 8% |
| Top spin 1⁄2 vs. Spin 0 | 2 | 3 | 4.5 |
| Rare decays t  c                    t  cZ | < 7.5  10-3< 4  10-2 | < 3  10-3< 1.5  10-2 | < 1.5  10-3< 7.5  10-3 |
| W mass:transverse massW/Z ratio method | 27 MeV44 MeV | 22 MeV28 MeV | 19 MeV20 MeV |
| W width (direct) | 32 MeV | 24 MeV | 18 MeV |
| sin2Weff (from AFB ) | 0.0007 | 0.00042 | 0.00028 |

**What counts for all of the above is luminosity ******** efficiency**

## Higgs sensitivity study

**CDF and D****Ø agreed to revisit the “famous” SM Higgs reach plot**
**CDF focus on WH channel**
**D****Ø focus on ZH channel**
**No combined results yet**
**What I have seen so far is rather encouraging **
**see next slide**
**Goal is to show to Ray Orbach on June 24**

## b-tagging studied with full GEANT simulation and pattern recognition

**b-tagging studied with full GEANT simulation and pattern recognition**

## Question 4: What strategy would the collaboration prefer?

## Why are we here?

**Fermilab has submitted to DOE an accelerator plan**
**There exists the implication that we should rethink the need for the Run IIb detector upgrades in light of this plan**

## What you expect me to say

**You might expect that I will stand up and say “we must still build the detector upgrades no matter what”**
**I am not going to do that**
**I know at least some members of the community, and of this committee too,  wonder whether upgrading makes sense **
**I am not going to argue what the right thing to do will eventually turn out to be**
**I am going to argue that ****now is not the time, and this is not the way, to reach such a conclusion**
**In fact “should we build the upgrades?” is not the right question to ask at all**

## The “spiral of death”

**Suppose we conclude something like this right now**
**“****In light of the presented accelerator plan, and the high technical risk of achieving the upper goals, we feel it is no longer prudent to invest in the detector upgrades”**
**The message we send is**
**“****We do not really believe the accelerator luminosity upgrades will pay off. Maybe not at all (base profile), maybe not in time to be useful”  **
**Why would anyone continue to invest in such accelerator upgrades? **
**They won’t.**
**What future does this leave for the collider?**
**Why would anyone then invest in any new accelerator facility at Fermilab?**
**“****After all, they can’t make things work” **
**Why would anyone then invest in any new accelerator facility in the USA, or want the USA as a technical partner?**

**We must not let this happen**

## Broader impact

**This is a big, visible, important question, not just for D****Ø**** or for Fermilab, but also for the future vitality of US accelerator-based HEP**
**Potential loss of trust in our commitments, reliability and capabilities**
**International impact**
**Potential loss of resources**
**One is starting to hear senior people saying semi-openly that they want to take resources away from Fermilab in light of the Run II outlook**
**I believe it is naïve to imagine that any such resources can simply be redirected**
**The perception of failure in a major HEP project will hurt us all**
- it certainly won’t increase the likelihood of any other major HEP project being supported
**Shooting inwards will hurt us all**
- How many times do we have to learn this lesson?
- At this point we simply must help one another succeed.
**University groups have even been told that their CDF/D****Ø**** work is hard to support when the program “seems to be failing”**

## What do we have to do

**The real problem here is our accelerator performance and the level of credibility attached to our projections, planning, and management**
**This is what must be addressed to get us out of the spiral**
**“****Addressed” means dealing with both the perception – the public image of how we are doing – and the reality**
**Descoping our goals may be part of this process, but by itself does  not constitute this process**
**If we do descope our goals we’d better be able to explain in a watertight way that it is because of unavoidable things like Maxwell’s equations and maybe the old age of the machine (perhaps even insufficient funds?)**
**If human factors (our competence, management or lack-of-will)****end up being blamed, then we are still in the spiral**
**Consider a stand-down from running the Tevatron, if necessary?**
**How can we help?**

## The detector upgrades

**Sacrificing the upgrades now will do nothing to**
**Enhance the credibility of the accelerator plan**
**Restore confidence in Fermilab’s ability to focus on and address problems**
**If indeed it does end up being the right thing to do, then it has to be because**
**We are really and visibly getting our act together **
**And as part of that process, we (as a community) have in the end convinced ourselves that **
**there are unavoidable limitations to accelerator performance**
**an overall optimization of resources is appropriate**
**doing so will help secure the future of the field**
**None of these conditions is now true. **
**It should not be done now, not in a rush because of a review, not this way, not based on this plan, and what little we know now.  **

## We always knew these upgrades were a gamble; we proceeded because the physics payoff was so significant.  
It still is. 

Investors will tell you that if you want to make real money, you have to be prepared to make risky investments.

**It still is. **
**Investors will tell you that if you want to make real money, you have to be prepared to make risky investments.**

**Risk**

## What we advocate

**What we advocate**

**We wish to see a wholehearted effort to get the most physics out of the Tevatron ****— a broad program — ****while it remains a unique facility in the world.  **
**This means that we should not back down from ambitious luminosity goals, but should work to put them on a firmer basis with a robust effort to address the technical and human issues that currently call them into question.  **
**The schedule is such that we cannot ask the detector upgrades to take a holiday while this happens.  We have to keep going full pace.**
**We should plan for success in the accelerator and we should not do anything that precludes taking full advantage of that success. **
**We should proceed with the upgrades while we get our arms round the accelerator situation**
**	****We have to be sure we get this right, for the future ****of Fermilab and for the field as a whole...**