# Presentation: 889949

## PHENIXNose Cone Calorimeter Upgrade

- Mickey/David/Ken

## A Brief Introduction to the NCC

**W-Silicon sampling calorimeter**

**Nose Cone Calorimeter**
**40 cm from interaction point****, 20 cm depth**
**2******** coverage in azimuth and 0.9 <  ********  < 3.0**
**W-silicon sampling calorimeter  **
**1.4 cm Mollier radius**
**42 X****0**** and 1.6 ********abs**
**Lateral segmentation 1.5x1.5 cm****2**
**3 longitudinal segments **
**2x2 tracking layers with 500 ********m strips**
****** ****separation for overlapping showers**

**Strip Tracking Layers (“PreShower” and “ShowerMax”)**

- EM1         EM2                      HAD

## Future PHENIX Acceptance for Hard Probes  

**MPC**

**MPC**

**-3              -2             -1                 0                1               2               3    rapidity**

****** ****coverage                 2******

**EMCAL**

**EMCAL**

**(i) ********0**** and direct ******** with combination of all electromagnetic calorimeters**
**(ii) heavy flavor with precision vertex tracking with silicon detectors **
**	****combine (i)&(ii) for jet tomography with ********-jet **
**(iii) low mass dilepton measurements with HBD + PHENIX central arms**

- Future PHENIX Acceptance for Hard Probes

## Spin Physics I – ΔG at low x

- Spin Physics I – ΔG at low x

- Gehrmann-Stirling models

- Current data is sensitive to G for xgluon= 0.020.3

***NEED TO EXTEND ***
***MEASUREMENTS TO LOW x!***

## Selecting x with rapidity cuts

- NCC.N
- All

- MPC
- NCC
- EMC

- Above plots are for jets into the acceptance of the specified detector.
- The more forward one goes, the lower one can go in x.  Also note one selects also a higher x parton along with the lower x one, simultaneously, so going forward isn’t just low x – it’s broader x coverage.
- NCC.N statistics for pt>4 GeV jets is 3x EMC and also 3x MPC.
- Two NCC would have 6 times the statistics of the EMC
- PYTHIA tells us if we measure the energy and rapidity of the 2 jets in a dijet we can explicity measure x with a best resolution on the x of 25%.  We need to fold in the detector resolution to determine the final x resolution.
-  The forward detectors cover from x ~ 10-3 to x ~ 1.... An order of magnitude lower in x than without them.

- MPC
- NCC
- EMC

- MPC
- NCC
- EMC

## G with NCC direct  ALL

- G with NCC direct  ALL

- Inclusive direction photon ALL shows a lot of promise in the NCC (gamma-jet or jet-jet should also be quite sensitive)
- At the present level of understanding, when we looked at a realistic analysis using the full simulation, there were two main problems:
- Isolation cut not as effective as central arm due to hadron response not being tuned and the lack of a spectrometer in front of the NCC.
- Direct Photon and 0 separation not quite good enough at the moment – Strip layers need to be understood better.

**GSA**
**GSB**
**GSC**

## Jet Energy Resolution

- Used Cone Algorithm R = (2 + 2) < 0.5
- Energy returned by reco software is ~0.66 times the pythia jet energy.
- Limited space, abs = 1.6, so there is a lot of leakage for hadrons   large constant term
- Limited momentum measurement of charged hadrons in front, but was not considered for this study
- More to be done.  This is lower limit of capabilities

## Jet Angular Resolution

- The jet angular resolution is vital to reconstruction of parton momentum fraction x in gamma-jet events, since the error in x is
- The difference in angles between the reco jet and the nearest parton from pythia one gets (,)=(0.04,0.05) radians.
- There is a tail of (0.16,0.18) radians, which is an artifact due to 3 jet events.
- The RMS of both distributions is ~ (0.1,0.1), giving an ~10% resolution on x, not so bad.

## Efficiency of Jet Finding

- Not too bad, about 70%.
- Below eta of ~ 1.2, the leakage is larger.
- Fiducial acceptance starts at 1.2, or R = 0.4 from edge.
- Vast majority of fakes are removed with the ET cut > 15 GeV.

- Reconstructed Jets
- PYTHIA Jets

## Gamma-Jet ALL

## Gamma-Jet ALL

## Spin Physics II: Transverse Spin

- Gamma-Jet AN, (A DOE Milestone)
- BBDMM, Phys.Rev.Lett.99:212002,2007.
- Very Complete Test of Theoretical Understanding of QCD as it is another test ISI or FSI contribution to asymmetry
- Direct Photon AN
- , , , K0S,...  AN

## Spin Physics III: W Boson with NCC

- With High Resolution Tracking (VTX and FVTX), the Inner Region becomes a miniature highly advanced silicon detector.
- There is enough Bdl in the ++ configuration to get a deflection which is on the order of the size of the detector elements

- 2 inner planes
- 50 um pitch
- 2 outer planes
- 80 um pitch

- VTX

## Determining We Charge Sign

- NCC

- Silicon Hit

- Wrong Sign Trajectory

- The NCC provides the electron momentum
- This is much better than the tracking can do
- The NCC also provides a hit position, which is beneficial due to the long lever arm

- Get Energy, primary vertex position, and NCC hit position
- Swim a positive track and a negative track, and look at the residuals to the silicon hits

- One Possible Algorithm (which is the one used in this talk)

- Effectively, because we measure the electrons momentum, we double the discrimination ability of the silicon
- Not sure if above algorithm is the best possible... Will investigate others

## VTX Hit Distributions

- We lose about 20% of the statistics due to holes in the top and bottom of the VTX
- I’ve been throwing everything at z=0 for now, but besides the acceptance (ie, how many VTX hits), this shouldn’t impact the W result that much.

## VTX Hit Residuals

**Positron**
**Electron**
**Wrong Sign Track**

- Residuals for the 4 VTX planes, in radians
- E resolution from NCC is included
- getting ~5% for E>20
- Primary Vertex Resolution = 50 um in all three dimensions
- NCC Resolution = 150 um in x and y
- So, when there is a hit in the outer VTX, we can determine straight away the charge sign.

## Vtx2 dphi vs vtx3 dphi

**Correct sign**
**Incorrect Electron**
**Incorrect Positron**

- The hits on the outer two VTX stations are highly correlated of course
- When one chooses the wrong sign for your track trajectory, the trajectory misses the hits (red and blue above)
- We can make a cut on fabs(dphi)<X to select the right charge
- If Outer Two VTX Stations are required, then the good region is shown as in above right for different zvtx ranges and hit positions on the NCC

## Efficiency and Charge Determination

- |eta|<1.5
- pt>20 GeV

- Charge Correctness

**Positrons**
**Electrons**

- Efficiency

- Max Efficiency

- From looking at just the outer two VTX stations, we can determine the charge sign correctly 90-95% of the time
- The max efficiency is limited to ~80% by the VTX holes at the top and bottom
- The rest of the efficiency loss comes from making tighter association (see figure), but also due to track missing the outer 2 stations as one goes to more forward eta
- Note the efficiency above only counts 1<|eta|<1.5

## Pt and Eta Distributions

- BLACK = AFTER CHARGE ID CUTS (ie, hit assoc to VTX2 and 3)

- W+

- W-

## Main Remaining Work: Backgrounds

- The hadronic backgrounds from jets are still to be determined and are the next crucial thing that needs to be understood.  However, thin calorimeters are naturally less sensitive to hadrons and we expect 1/500 rejection
- Expect very good rejection from longitudinal cuts (3 segments) and transverse cuts (strips)
- Isolation cut
- Missing ET.  With 2 NCC, MPC, VTX, PHENIX starts to become a high acceptance detector.  This hasn’t been adequately studied yet.
- What about the Z0?  Is a second NCC required?  The Z decays largely at rest (back to back)

## NCC physics  measurements and detector requirements

## Near Future Plans

- readout sections

- Waveshifting
- fibers

- PHENIX has $200K in this fiscal year for Forward Calorimeter R&D
- The money will go towards building a prototype along the original design
- Beam Test Scheduled for FNAL early next year
- HERA-B has a W-Sc calorimeter, we might be able to get a prototype from them
- Possibly reuse their W and scintillator

- Study of the gamma/pi0 identification
- This is crucial to removing the large pi0 backgrounds to the direct photon, but once done allows gamma and gamma-jet which greatly enhances the RHIC spin program
- Recent work on more sophisticated algorithms promising
- Highly Correlated Multi-Dimensional Problem
- Studying in GEANT4 whether more Strip Planes will solve the problem

## W with NCC Prototype In Run09?

- If we have a prototype that works, we have the freedom (power) to put it where we want
- Small detectors can have a large acceptance if it is close to the IP
- We expect to have a 12”x24” prototype for Run09, with the possibility of a 2nd prototype
- We could put the detector at mid-rapidity or more forward (up to y=1.5)
- Forward has lower rate, but higher asymmetry
- Possibility of having some VTX prototypes  AL(W)

- 12”x24” NCC Prototype
-  = 0

## Tentative RHIC Run Plan Following 2008 PAC Recommendations

| Fiscal Year | Colliding Beam Species/Energy | Comments (NCC Contributions in red) |
| --- | --- | --- |
| 2009 | 500 GeV p+p | Assuming ~April 1 start, about 5-6 physics weeks to commission collisions, work on polarization & luminosity and obtain first W production signal to meet RIKEN milestone |
| 2010 | 200 GeV p+p | ~12 physics weeks to complete 200 GeV ALL measurements – could be swapped with 500 GeV Run 9 if Run 9 can start by March 1, 2009; STAR DAQ1000 fully operational |
|  | 200 GeV Au+Au | 9-10 physics weeks with PHENIX HBD, STAR DAQ1000 & TOF permits low-mass dilepton response map and 1st collision test of transverse stochastic cooling (installed in one ring) |
| 2011 | Au+Au at assorted low E | 1st energy scan for critical point search, using top-off mode for luminosity improvement – energies and focus signals to be decided; commission PHENIX VTX (at least prototype) |
|  | 200 GeV U+U | 1st U+U run with EBIS, to increase energy density coverage |
| 2012 | 500 GeV p+p | 1st long 500 GeV p+p run, with PHENIX muon trigger and STAR FGT upgrades, to reach ~100 pb-1 for substantial statistics on W production and G measurements |
|  | 200 GeV Au+Au | Long production run with full stochastic cooling upgrade implemented, PHENIX VTX and prototype STAR HFT installed; focus on RHIC-II science goals: heavy flavor, -jet, quarkonium, multi-particle correlations |
| 2013 | 500 GeV p+p | Reach ~300 pb-1 to address 2013 DOE performance milestone on W production and sea antiquark polarizations |
|  | 200 GeV Au+Au or                       2nd low-E scan | To be determined by results from 1st low-E scan and 1st upgraded luminosity runs, progress on low-E electron cooling, and on installation/commissioning of PHENIX FVTX and NCC and full STAR HFT |
| 2014 | 200 GeV Au+Au or                       2nd low-E scan | Run option not chosen for 2013 run – low-E scan addresses 2015 DOE milestone on critical point, full-E run addresses 2014 (-jet) and 2016 (identified heavy flavor) milestones. Proof of principle test of coherent electron cooling |
|  | 200 GeV p+p | Address 2015 DOE performance milestone on transverse SSA for -jet; provide reference data for HI runs with new detector subsystems; test electron lenses for p+p beam-beam tune spread reduction |

**Tentative RHIC Run Plan Following 2008 PAC Recommendations**
- (assumes 6-month CR in FY09, then FY10-14 budgets sufficient to support 2-species runs each year; incorporates best available information on detector upgrade schedules as of 6/20/08)

## Backup Slides

## A Brief Introduction to W Spin Physics

- M. Hirai, S. Kumano, N. Saito, Phys. Rev. D 74, 014015 (2006)

- The W boson in polarized proton collisions gives a unique ability to study the flavor dependence of quark polarization
- The W maximally violates parity (V-A); large analyzing power
- Selecting different y and pT regions allows one to measure the polarization by flavor

## Tracking calorimeter doesn’t need to be projective!!!

- 10 GeV electron
- y=1
-       center of gravity of
- cluster
- Like pixel tracking
- three layers+vertex
- iteration assuming
- parameterization of
- shower shape for cluster
- sharing etc

- EM1

- EM2

- HAD

## Where the tail in dphi, deta comes from

- Due to radiative effects (~ NLO effects), in pythia ~10% of the time the outgoing jets might not be the jets that we should compare to (it is known to be difficult to track down the color flows to find the right jet).
- If one uses independent fragmentation, one can trace the fragments back to the right jets.  To make things even less ambiguous, final state radiation was turned off.
- With unambiguous identification with the underlying pythia jet, the resolution very good, about 2 in phi!

## NCC extends x reach

- number of events

## GS-C at 500GeV direct photons

- assume 70% polarization

- NCC is sensitive to low-x
- e.g. behavior of GS-C

## G with Jets in the NCC

- G with Jets in the NCC

- First look at some basic things, to see what things look like if we had a perfect detector
- Used PYTHIA 6.319 with hard QCD and minimum jet pt of 4 GeV
- Q1: How well can one reconstruct the partonic x ignoring detector effects, using the well known relations
- ~25%, with a long tail and a systematic offset (40% RMS including the tail)
- Dominantly from radiative effects

- Log10(x)

- 1<yjet<3
- Red = x1
- Blk = x2

## VTX, FVTX, NCC in PISA

**Was drawing pictures to make sure things were working when the disks went to hell last night**
**Have some vague idea how to do the tracking**
**Dave W. et al have been doing studies for optimizing the FVTX design, and have tracking with the mutoo Kalman filter going.**
**Still a bit rough, eg, they use smeared VTX positions from the pisa hits info.**
**Put in a GEM for a 50 um hit position in inner radius of NCC, want to extend the acceptance = NEW PHYSICS (should separate this out as a different project).  Requires NO HAD section.**
**Want to study region of good sign determination using full simulation (measuring deflection on NCC is better than sagitta)**
**Actual background rejection using full simulation**
**Charged Hadrons**
**Pi0 dalitz, conversions, pi0+overlapping track**
**Time scale: hoping for 2-4 weeks**

- SVX

## single shower π0 

- PS

- Total Energy – from pads
- Opening angle – from PS
- Energy asymmetry – from SM
-  invariant mass

- SM

- eff ~40%