# Presentation: 406638

## Ncc Meeting

- Sep 20 3007

## New news

- date for NCC Cost-schedule review ~mid Jan- date not finalized
- we must have our document to DOE by end of Nov
- We must have our document to the collaboration for review by ~mid-Nov
- The committee (the same previous committee) must pass us on the physics review before the Cost and Schedule review but the scheduling of that review is being done now
- The cost and schedule committee will be a new committee

## Couple things

- I will be doing a better low energy correction, which may be a function of angle as well (does it have to be theta AND phi?)
- I am starting hijing studies of suppression

## DOE review

- Summary:
- Review July 9-10
- Committee: **R.Roser (FNAL) P.Reimer (ANL) H.F.W. Sadrozinski, (UC  Santa Cruz) L.Ray (Austin) H.Crawford (UC) M. Murray (Kansas) **
- Presentations not received well
- Final report available since August 29
- Unchanged very negative wording
- Look at recommendations only
- Recommendations:
- Each detector group should demonstrate and document scientific feasibility for two or more topics of high importance and submit to DOE for evaluation. PHENIX should submit to DOE a report documenting these studies for evaluation, prior to a technical review.
- The NCC group should demonstrate by simulations that the non-projective geometry and shower digitization does not preclude the ability to eliminate background at the level necessary to accomplish the proposed physics goals. PHENIX should submit to DOE a report documenting these studies for evaluation, prior to a technical review.
- Course of action: Write independent reports for NCC and FVTX prior to technical review (slipping to November 14-16)

## Topics of High Importance

- Heavy ions
- Gamma jet tomography
- Heavy flavor
- C  J/ + 
- Spin
- DG via ALL
- Transversity (single spin)
- Sivers effect in DY

**Identified in DOE review report**

**Our proposal for reports**

- NCC
- C  J/ + 
- Gamma and pi0

**Potentially also address DY and color glass condensate??**

## Main tasks:

- Technical details: full Monte Carlo simulations
- Tracking (FVTX)
- Gamma (pi0) reconstruction (NCC)
- Extraction of observables
- RAA, ALL and so on
- Relate to current theoretical models
- Energy loss
- Screening length
- G

**This will also address**
**“****non projective” geometry issue**

**2 hours devoted to status reports at Wednesdays DC meeting**
**Plan how to proceed and what the timeline is after DC meeting**

- we will need this to for
- the chic

## What we think was missing

- Simulations
- complete explanation of the detail that went into the current simulation work
- Better presentation of step-by-step analysis required so that it is better understood what simulation detail is needed at each stage
- Simulation of signals in an Au+Au environment
- Physics Measurement
- presentation of extraction of physics from measured quantities (e.g. energy loss mechanisms from RAA)
- screening length from chic

## NCC Review Response - Selected Physics

- Heavy Ion
- pi0/direct photon measurements to understand energy loss in the medium
-  Chic measurements needed to understand screening
- Spin
- Precision direct photon measurements give gluon contribution to spin, over much larger x range
- dAu?

## my outline

- Exec summary
- 1) Introduction
- strategy of the report
- physics
- two topics
- structure of detector
- how the detector works
- Introduction to how the simulations were done
- event Generation
- generate backgrounds
- For both run through PISA(GEANT)
- for both generate detector response
- Merge signals at the raw signal level
- pattern recognition
- reconstruction
- extraction of signal
- 2) Pattern recognition and photon/pi0 reconstruction
- shower shape
- clusters
- tracks
- Energies and angles
- PS/SM and pi0
- 3) detector performance
- Calibration corrections
- non-projective geometry
- nice pictures of showers
- Eff vs angle photon
- eff vs angle pi0
- show eff for pi0, photon vs multiplicity

## my outline cont

- Real time digitization
- show test beam result
- show digitization on and off for photon, pi0
- Energy resolution
- simulation
- test beam
- 4) Pi0’s and direct photons
- pi0 performance in high multiplicity events
- efficiencies etc
- Extraction of pT distribution
- direct photon analysis – high multiplicities
- Heavy Ions
- Extraction of signal
- R_AA vs pi0, vs pt, centrality, rapidity
- Physics interpretation
- dAu
- Extraction of signal
- Physics interpretation
- spin
- extraction of signal
- physics interpretation
- Jets
- jet finding
- resolution in x
- 5) Chic analysis
- chic heavy ions
- extraction of signal
- R_AA vs pt, centrality
- physics interpretation
- 6) Conclusion and summary
- Appendix 1
- Luminosity assumptions

## OK?

- Is this OK
- If So I will set up a CVS area
- 5 chapters
- Intro
- Pattern recognition and reconstruction
- Detector performace
- pi0’s
- chic
- conclusion
- Appendices
- Lums etc

## Intro more detail (no more detail)

- 1) Introduction
- strategy of the report
- physics
- two topics
- structure of detector
- picture – simple pictures of Si-pad, 3 kinds of brick, a stack of 3 bricks, whole detector
- how the detector works
- Introduction to how the simulations were done
- event Generation
- generate backgrounds
- For both run through PISA(GEANT)
- for both generate detector response
- Merge signals at the raw signal level
- pattern recognition
- reconstruction
- extraction of signal

## New picture 

- New picture

- Silicon pads
- 1.5x1.5 cm2

- Tungsten 4 mm (EM) & 12mm (HAD)

-  500 um pitch Strips (“StriPixels”)

-       EM1
- electromagnetic

-       EM2
- electromagnetic

-         HAD
- hadron identifier

-     SM
- “shower max”

-     PS
- “pre-shower”

- Depth:  42X0  (1.6 λABS)

- 16x
- 16 pads
- per towerlet

- What is the black?
- yellow
- blue?

## slides of brick etc

## patter rec and reconstruction more detail

- Pattern recognition and photon/pi0 reconstruction
- shower shape
- clusters
- tracks
- Energies and angles
- PS/SM and pi0

## Angle studies

- 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

## Shower Shape studiesfor now parmetrize as 1/r -

- EM1

- EM2

- HAd

- towers

- towers

- clusters

## detector performance more detail

- detector performance
- Calibration corrections
- non-projective geometry
- nice pictures of showers
- Eff vs angle photon
- eff vs angle pi0
- show eff for pi0, photon vs multiplicity
- Real time digitization
- show test beam result
- show digitization on and off for photon, pi0
- Energy resolution
- simulation
- test beam

## 20 GeV y=1.1

## hole in acceptance ~2.5-3recover some with partially contained showers?

- hole in acceptance ~2.5-3recover some with partially contained showers?

## eff vs y for 5 GeV Showers

- Delta E cut
- required 1 sigma
- (so max ~94%)
- need to do vs
- multiplicity

- need photon/pi0 eff high multiplicity as a function of angle

## Test beam With electronics (full chain to HBD ADC)

## new cable at test beam100 GeV electron

- width=5%
- =727/14740
- 23%/sqrt(E) ~ 2.3%
- no channel to channel
- calibrations yet

## What is it?The parts of the NCC

- 30 GeV
-     π0

- The PS and SM
- Detectors:
- identifying π0s

-  500 um pitch Strips (“StriPixels”)

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

## pi0 direct photon detail

- Pi0’s and direct photons
- pi0 performance in high multiplicity events
- efficiencies etc
- Extraction of pT distribution
- direct photon analysis – high multiplicities
- Heavy Ions
- Extraction of signal
- R_AA vs pi0, vs pt, centrality, rapidity
- Physics interpretation
- dAu
- Extraction of signal
- Physics interpretation
- spin
- extraction of signal
- physics interpretation
- Jets
- jet finding
- resolution in x
- figure out rapidity, pt distribution of single pi0
- look at rapidity,pt distribution of hijing
- Figure out acceptance of pi0 from full analysis
- use lum numbers and cross section to figure out number of events
- Find S/B from full analysis
- scale the distributions split into pt and rapidity bins
- correct for acceptance etc
- make a pt spectrum, find yield
- make R_AA

## single π0  simulations 

- PS

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

- SM

- old slide of illustration

- 2-track

- single-track

- new simulation

- old slide of illustration

- NEED NEW PLOTS

- NEED NEW PLOTS

## merged into pp

- two track, 5-10Gev

- two track, 10-15Gev

- single track, 10-15Gev

- single track, 10-15Gev

- Signal – pi0’s with pt spectrum
-   put in by hand
- background – pythia with “real”
- pi0’s concentrated at low energy

## pp merged – single track pi0’s

- 15-20 GeV

- 20-30 GeV

- 30-40 GeV

- 40-50 GeV

## raw pt distributions

- single pi0

- merged pi0

- black – original signal of pi0’s
- red – merged reconstruction

- I suspect this is the
- background coming
- in

- Signal – pi0’s with pt spectrum
-   put in by hand
- background – pythia with “real”
- pi0’s concentrated at low energy

## Pi0 plots at higher multiplicity

- pi0 efficiency

## pi0 R_AA

## pi0 comparison to models

## pi0 continued

- Give Takao Eff of finding pi0 and pi0 spectrum
- Takao extract direct photon distribution
- Do a study of hijing with different suppression vs rapidity
- look at papers and talk to people
- find FMS capability
- what is STAR’s way of doing things (eta/phi bins)

## pi0/gamma spin detail

- get pt distributions for pi0 as above
- get eff for pi0 in pp
- Give to Takao – extract direct photon spectrum
- Weight using spin dependent structure functions – extract direct photon

## direct photon

## pi0/gamma spin continued

- Ask werner for a pt direct photon from a few delta G(x)
- fit to simulated data.
- For high pt, show jet resolution, direct photon
- x_1 and x_2 resolution

## NCC Jet Studies (Mickey)

- 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

## 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, not quite the 10x we always quote?
- So far so good.. 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

## PYTHIA Parameters for this Study

- I started with a cut of pt = 4 GeV but this is way too low, so I also ran 10 and 15 GeV pt cuts, where pt is the pt of the jet
- No other cuts were made, ie, all events were kept and processed through PISA
- This is the most similar to the real world, where there is a collision and you don’t know where the jets are going and you just try to see if there is a jet in your detector and if those reconstructed jets are similar to what you threw in.
- In any case, 15 GeV is ~ the threshold that one might be able to trigger at, since we require L < 1000 Hz,  and for L = 2x1032cm-2s-1 this is  ~ 5 ub, and according to PYTHIA (pt>15) = 6 ub.
- Also note that about half of all jets are in the NCC acceptance, so that is effectively more like 3 ub.

- PYTHIA 6.319 (the current version in the offline software (PHPYTHIA)
- s = 500 GeV
- CTEQ5L
- Hard pQCD (ie, 22) Only (MSEL=1)

## Jet Cone Algorithm, using Towers

- The Jet reconstruction is done by summing up the towers in a cone of radius R  (2+2) < 0.5.
- A tower is defined as the sum of the pad energies in a compartment (EM1, EM2, Had)
- The tower position was determined from the centroid of the compartment, (possibly centroid of energy deposition is better, but needs to be studied).

- Find the highest ET tower (the “seed”).  This is the best guess at the initial axis of the jet.
- Sum up all the towers in the cone radius, treating each tower as a vector, and calculate the new jet axis.
- Repeat step 2 until we reach convergence, ie, the jet direction is stable.

- The algorithm (this is a very standard algorithm):

- Note that there are many different possibilities for improvement
- Try Other algorithms (kT jet, neural network, etc).
- Use twrclusters (ie, Edouard’s clustered towers) instead of simple towers
- Tune Parameters (jet cone radius, thresholds, etc).
- I did this for each arm, ie, I reconstruct 1 “jet” in each arm, and then for each reconstructed “jet” I look for the nearest jet and compared to that jet
- In the following slides I show some low statistics from pt > 10 and 15 GeV PHPythia/PISA studies

## Jets in the NCC

- In the above NCC display, there are pt ~ 15 GeV jets headed to
- NCC.N  (23.2, -3.66) and NCC.S  (-2.41,2.37)
- The north looks fine, but the south has a lot of the energy escape elsewhere
- Does this cause many fake jets because one can’t tell backgrounds or even the fragments from a jet to the real jet?
- I’ll show later that all these fake jets are at lower ET, so at high enough ET the fake rate is low.

- Note the towers energy is placed in the x,y position of the front face of the NCC, while the energy gets deposited at a constant angle into the NCC, giving a elongation outward from center in the above display

## Jet Angle

- dphi, deta are the angles of the reconstructed jet from the pythia jet
- There initially seems to be some nicely reconstructed jets, but with many fake jets, ie, jets which do not associate with the underlying jet (grass in the above plots)

- Pt > 10 GeV

- Pt > 15 GeV

- deta

- dphi

- deta

- dphi

## Energy Resolution

- d>0.25&&d>0.25
- d<0.25&&d<0.25

- Pt > 10 GeV

- Pt > 15 GeV

- d>0.25&&d>0.25
- d<0.25&&d<0.25

- Looking at the jet energy resolution of the associated jets vs those which are not associated, the unassociated jets are clearly mismeasured.
- The energy resolution of the associated jets is about 36% at 15 GeV, so I am seeing about dE ~ 120%/sqrt(E)
- The reco jet et was scaled by 1.5 to account for the charged hadron energy which is missed.
- Also, the fake jets almost all go to lower energy, though there is a high side tail.
- At high enough pt, the backgrounds should go way down?

## Jet ET vs alpha

- Pt > 10 GeV

- Pt > 15 GeV

- Alpha is angle between pythia jet and reconstructed jet (similar to dphi,deta cuts).
- If we require that the reconstructed jet ET*1.5>10 (15 GeV), the fake jet rate goes way down.
- What remains is at least partly from 3-jet events, so we always expect some grass at 10% level.
- The jet angular resolution, ignoring the tail, is ~7.5 degrees (0.13 radians).

## Some Other Possible Cuts

- Looked also at some other possible cuts, such as the seed ET, total ET, total number of towers in NCC, and the towers in the jet cone.
- Most aren’t helpful... Possibly the number of towers in the cone can help.
- Needs more study

- Pt > 10 GeV

- Pt > 15 GeV

## Jet Reconstruction Efficiency

- Pt > 10 GeV

- Pt > 15 GeV

- All events
- d<0.25&&d<0.25

- All events
- d<0.25&&d<0.25

- Associated jets have relatively low efficiency... seems to be about 50%.

## Summary

- A highly realistic simulation through the full PHENIX chain (PHPythia,PISA,Edouard’s reconstruction code) has been done for jet events.
- Jets have been successfully reconstructed in the NCC, using a simple cone algorithm on towers, with an angular resolution of ~7 degrees and energy resolution of 120%/sqrt(E).
- There is some amount of background from fake jets, but these are reduced as one goes to higher and higher pt.
- From here, there are many things that can be done
- Calculate how well one can do various physics measurements with the current jet reconstruction
- Investigate improving the jet reconstruction algorithm
- Try different algorithms
- Tune various parameters
- Use Edouards twrCluster (which are clustered towers)
- Investigate different cuts to reduce fakes
- Investigate real backgrounds to jet measurements (like direct photons, etc)

## What can jets add for delta G

## chic detail

- Chic analysis
- chic heavy ions
- extraction of signal
- R_AA vs pt, centrality
- physics interpretation
- look at rapidity, pt distribution of rvchi
- look at rapidity,pt distribution of hijing
- Figure out acceptance of chi from full analysis
- use lum numbers and cross section to figure out number of events
- triggering!
- Find S/B from full analysis
- scale the distributions split into pt and rapidity bins
- correct for acceptance etc
- make a pt spectrum, find yield
- make R_AA

## delta E/E for 1-1.5 GeV

- sigma~23%
- mean=0.13

- Photons

## J/psi width ~100 MeVwith fvtx stuff from melyndaneed to work on additionalclean up cuts

## before

- after

- quick and dirty energy
- correction
- (needs to be done MUCH
- more carefully – function
- of angle etc)

## Width of chic ~100 MeVwith Energy recal

- from TDR

## now on to pp pythia events

- Procedure
- use known photon (closest one)
- Cuts
- Chisq_ncc<10
- E_ncc(corrected)>0.5GeV

- chic_real

- background

- all events

## harder cuts

- Cuts
- chisq_ncc<20
- E_ncc>1
- pt_photon>0.5

## chic plots in AuAu etc

## Counting question

- Should get 10K chic in central events in 1 yr run
- Real question is what is will S/B be?
- Things that help
- dN/dy of pi0 ~1/2
- J/psi width reduced by FVTX  by 1.5
- rejection of hadronic decay-DCA cut (needs to be studied)
- TRIGGERING

##   χC RAA    1<y<1.5 12 Weeks RHIC IIcompared to present J/ψ 

-   χC RAA    1<y<1.5 12 Weeks RHIC IIcompared to present J/ψ

- χC stat only

- ~50K total χC
- For 0-10% Central
- 10K signal
- 600K background

- J/ψ→e+e-

- J/ψ→μ+μ-

- NEED NEW PLOT

## chic continued

- Look at suppression models

## Summary

## Appendix Lums

- RHIC II
- pp 200-238 pb-1   pp 500 1195 pb-1
- AuAu 18 nb-1
- RHIC I
- pp 71 pb-1
- AuAu 2.4 nb-1