# Presentation: 090750

## ALICE Reconstruction

**Tracking**
**Vertexing**
**Particle Identification**
**Performance**
**Planning**

## Progress during last years

**Reconstruction**
**parallel tracking**
**improvement in ITS tracking**
**new TRD tracking**
**reconstruction of charged kaon decays in TPC**
**progress in combined particle ID**
**Physics performance**
**pp collisions**
**charged kaon production**
**HBT performance**
**charm production in pp and pA**
**beauty production study**
**update on dimuons – centrality **
**jet quenching**
**gamma – jet **

## ALICE Detector

**TPC**

**PHOS**

**Muon arm**

**TOF**

**TRD**

**HMPID**

**PMD**

**ITS**

**ALICE Detector**

## Tracking strategy

**Iterative process**
**Forward propagation towards to the vertex –TPC-ITS**
**Back propagation –ITS-TPC-TRD-TOF**
**Refit inward TOF-TRD-TPC-ITS**

## Tracking strategy – Kink and V0 finding strategy

**Iterative process for mother and daughter particles (Continuous seeding –track segment finding in all detectors)**
**Forward propagation towards to the vertex –TPC-ITS**
**Back propagation –ITS-TPC-TRD-TOF**
**Refit inward TOF-TRD-TPC-ITS **
**Kink topology finding, storing  and updating (refitting) with the best Kalman parameters**

**Daughter particle**

## Cluster finder

**Cluster finder looks for local maxima in digit two dimensional time x pad space**
**Neighbourhoud  - matrix 5x5 with maxima at center investigated**
**RMS  fitting of the cluster **
**Virtual charge introduced (signal bellow threshold replaced by expected value according gauss interpolation)**
**COG of the cluster  interpreted as intersection position of the track with the center of padrow **
**Signal shape (RMS) used for later error estimation -and as a criteria for cluster unfolding**

## Gauss fit of the cluster

- Almost perfect agreement with the data
- Sigma of  residuals from measured values ~ 1.7 which is comparable with the applied noise
- But time consuming
- Not possible to use for overlapped clusters

##  RMS fit  of the cluster

- Applying virtual charge almost the same results as fit
- Sigma of  residuals from measured values ~ 1.9 which is only little bit worse than fitting method
- Space resolution the same

##  RMS versus fitting

## Cluster unfolding

**Theoretical signal shape (RMS's) are calculated**
**RMS ~ sresponse+sdif+sangle**
**If one of the RMS's – in time or pad direction bigger then critical RMS - unfolding **
**Fast spline method for unfolding is used**
**Charge conservation**
**small systematic effect **

## Cluster types in silicon drift detectors

**cluster types **
** ****type <100 – clusters with accepted charge matching**
**type >100  - “combinatorial” clusters with non acceptable or ambiguous charge matching **

**Cluster type**

## Cluster shape parameterization

**new cluster shape parameterization **
**linear dependence on the local track angle in θ and ****φ**** (known only during tracking procedure)**
**dependence on the layer width and the granularity – different for each layers **

## Cluster sharing probability parameterization

**cluster can belong to the more than one track**
**probability as a function of the distortion from the expected cluster shape parameterized**

**non shared cluster**

**shared clusters**

**N digitsM-NdigitExp**

## Cluster error parameterization

**if a constant effective errors are used -  pulls have long tail – χ2 criteria for the selection of the best track candidates is not optimal**
**using of the information about the distortion of the measured cluster shape from the expected one, and about the distortion of the measured cluster charge from the expected one**
**different types of the parameterization for each layer and cluster types **
- 3 % gain in the tracking efficiency**  **

**Y pulls**

**Z pulls**

**constant error**

**parameterized error**

**constant error**

**parameterized error**

## ITS tracking

**starting point **
**track seeds from the TPC**
**follow tree of track hypothesis connecting  reconstructed clusters **
**following cases taken to the account**
**track in dead zone**
**missing clusters (for 0.5% of the references not corresponding cluster found)**
**track cross dead ITS channel – (map of dead channels still not available)**
**cluster bellow threshold**
**track cross noisy ITS channel – (not yet in the simulation)**
**secondary tracks not cross ITS layer as function of impact parameter in z and r-****φ**
**probability of the cluster to be shared as a function of the cluster shape**

## New track tree building algorithm 

**old algorithm – track each branch separately down to the layer 0**
**new algorithm – **
**after each layer track hypothesis sorted according χ2**
**only gold track branches plus restricted  amount of non gold tracks prolongated further down**

**layer 5 –**
**2 hypothesis**

**layer 4 –**
**6  hypothesis**

**layer 3 –**
**18  hypothesis**

**layer 2 –0**
**too many hypothesis**

**Best track**

## Parallel tracking

**for each seed,  tree of the track hypothesis constructed**
**current best track according χ2  chosen**
**restricted amount of tracks kept for further parallel tracking procedure**
**for secondary tracks also short best tracks kept, for further V0 study **
**best track is registered to the all clusters which belong to the track **
**overlap factor between the best track and all other tracks is calculated**
** ****if the overlap factor is higher than a critical, χ2 of the pair of tracks is calculated **

## Parallel tracking

**double loop over all possible pair of branches**
**weighted χ2 of two tracks calculated **
**effective probability of cluster sharing and for secondary particles the probability to don’t cross given layer taken to the account  **

**Best track 1**

**Best track 2**

**Conflict !**

## Tracking efficiency (new TRD)

**For realistic particle densities**
**dN/dy = 2000 – 4000**** **
**combined efficiency well above ****90%**
**and fake track probability below ****5%**

## New TRD tracking – resolution

**at low momentum dominated by**
**- ionization-loss fluctuations**
**- multiple scattering   **

**at high momentum determined by**
**- point measurement precision**
**- and the alignment & calibration **
**(*****which is here assumed ideal*****)**

## Example - K0s

**Invariant mass spectra near K0s peek (Hijing central collision)**
**~30 K****0****s**** **

## Λ Reconstruction with pt dependent geometrical cuts

_**__* *__*Efficiency ~ 50 %*_

- 13 Λ / event

- S/N ~ 1.2

*10 000 000 Pb+Pb events*

- signal noise

********* ******= Acc * Eff***

*********0****** yield***

**Notes:**
Results on Pt dependant geometrical cuts

## -  Reconstruction

- B = 0.5 T dN/dy = 4000   	45o< 100 Λ + 100 Λbar < 135o
- 			45o<  15 Ξ  +  15 Ξbar  < 135o

- 

- 

- p

- bV0

- dca

- b

- cos 

**Acc=10%**
**Eff=3%**
******=0.3%**

_***Cuts for ***__******__*** :***_
- b- = 0.2 cm                b+=0.06 cm               dca=0.06 cm  costheta=0.995

_***Cuts for ***__******__*** :***_
- bV0 = 0.1 cm                b=0.12 cm               dca=0.06 cm  costheta=0.9995

- 0.05 /evt

## Kaon decays finding efficiency

**Search for ****K****±****→****μν**** decays in TPC**
**B.R. ****≈**** 63%; c****τ**** ≈ 370 cm**

**Momentum & multiplicity dependence **

**improvement with TRD**

## Kaon qt resolution

**Separation between ****K****±****→****μν**** (q****t****max**** = ****200 MeV****) and ****π****±****→****μν**** (q****t****max**** = ****30 MeV****) using ****q****t**** cut**

## Acceptance Purity and contamination

**Acceptance for ****K**** decays at p****t**** 20 GeV is ~ few ****10****-3**
**pp cross section at p****t**** 20 GeV** **is ****10****-4**** ****of minimum bias**
**about ****100 K**** at p****t**** ~ 20 GeV for ****10****9**** pp events (one year)**
**similar limit for ****10****7**** ****Pb-Pb events  (one year as well)**

## Combined PID : first experience

- _“__Raw” PID signals_

## Extension  of PID to even higher momenta

**Combine TPC and TRD dE/dx capabilities (similar number of samples/track) to get statistical    ID in the relativistic rise region**** **

## Combined PID

**Step 1 : ESD preparation  (“once and forever”)**
**For each track and for each of the detectors              **
**     ****a) calculate the PID signal (done by the detector trackers).**
**     ****b) calculate the *****R(mi|s)*****  (done by detector specific PID classes).**
**     ****For each track**
**           ****c) calculate *****R(M|s)*****  (done by some  class responsible for the combining).**
**  **
**     ****Write out the ESD****.**
**Step 2 : Data analysis (as many times as needed)****  **
**(done by the analysis macros/classes)**
**     ****a) Select the subset of ESD tracks under interest.**
**     ****b) Estimate the particle composition ( *****C(s), s=e,************,************,... *****) of the selected  track subset.**
**     ****c) For each of the selected ESD tracks calculate the PID weights *****P(s|M)  *****(by means of **
**         ****Bayes’ formula).**
**     ****d) Proceed with the analysis using the PID weights...**

- “Two step”  PID procedure

- I. Belikov

## Combined PID : first experience

## Combined PID

***N***** – number of tracks in the selected set of tracks.**
***Mi***** *****= {mi(ITS), mi(TPC), ...}***** – vector of the PID signals in the detectors (ITS, TPC, TRD, ...) by the i-th track.**
***C(s)***** – percentage of the particles of *****s*****-type in the selected set of tracks.  **_**Depends on the selection and does not depend on the detector   properties !**_
** *****R(Mi|s)***** – probability to observe the vector of signals *****Mi*****, if the detectors register a particle of *****s*****-type.  **_**Depends on the detector properties and does not depend on the track selection !   This is the result of the “PID combining” and this is what goes to the ESD.**_
***P(s|Mi)***** – probability to be a particle of *****s*****-type, if the vector of signals in the detectors was *****Mi***** .  This is what we want to get (the PID weight).**

- _Bayes theorem and the combined PID_

-     *R(Mi|s)C(s)*
-   __*R(Mi|t)C(t)*     *t = e, ****, ****, ...*

*P(s|Mi)=*

*s = e, ****, ****, ...*
*i = 1, 2, ..., N*

- I. Belikov

## Combined PID

**Probabilities *****R(mi|s)***** can be calculated for the “detector response functions” of any shape (not only Gaussian).**
**The “detector response functions” do not have to be the same for each of our detectors. **
**If, in some case, the resolution of some of the detectors is so bad that particles can not be identified at all, this formula is still valid. The contribution of such a detector simply cancels out.**
**This formula allows combining PID signals, first, only within a subset of the detectors and then (if it becomes possible) one can include the signal from an additional detector (or another subset of detectors).     **
**This is the responsibility of the detector *****D***** to provide the final PID procedure the probabilities *****R(mi|s).*****  These probabilities can be calculated if the detector knows its “response functions” for the particles of the s-type (s = e, ********, ********, ...).  **

- _Combining detectors’ PID signals_

*R(Mi|s)=*

-   *R(mi(D)|s)*
*    **D*

-   *R(mi(D)|t)*
*  **t    D*

- D = ITS, TPC, TRD, ...
- s = e, , , ...

- I. Belikov

## Combined PID : first experience

- _Status of the combined PID_

|  | Efficiency(%) | Contamination(%) | # of ESD tracks |
| --- | --- | --- | --- |
| Pions |       98 |            1 |       17337 |
| Kaons |       93 |           20 |        1566 |
| Protons |       97 |            6 |        1324 |

- 14 central HIJING events,  0.5 T field

- ~130000 ESD tracks found in the TPC,
-   ~30000 ESD tracks with selection ITS&TPC&TOF.

## Combined PID : first experience

- _Getting the response functions   _

- ITS

- TPC

- TOF

## PID combined with ITS, TPC and TOF

- Efficiency of the combined PID is higher (or equal) and the contamination is
- lower (or equal) than the ones given by any of the detectors stand-alone.

- Kaons with ITS & TPC & TOF (central Pb-Pb HIJING events)

## Efficiency & Contamination for combined PID

## Example : Particle spectra

**Needs corrections for decays, tracking and PID efficiency**

- I. Belikov

## Example:  analysis

- All candidates from the ESD
- S ~ p0 = 124
- S/B ~ p0/p3 = 1.9

- PID with C : CK : Cp = 1 : 0 : 1
- S ~ p0=127
- S/B ~ p0/p3 = 7.1

- (290 events from the jet production)
- Fitted with  p0*exp(-0.5*(x-p1)*(x-p1)/p2) + p3
- Mass=p1=1115 MeV   =√p1=1.3 MeV

- I. Belikov

## HMPID (RICH) performance

**HMPID (RICH) performance**

**p/K separation**
**3******** @ 5 GeV/c in Pb-Pb**

## pp dN/dη and multiplicity (ITS tracklets)

**pseudo-rapidity distribution**
**with two innermost pixel layers**

**Multiplicity distribution with **
**two innermost pixel layers**

## pp η and pt distributions (ND events)

**pp ****η**** and p****t**** ****distributions (ND events)**

## HBT correlations – resolutions 

| pt range [MeV] | Resolution (r.m.s) [MeV] |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- |
|  | Qout |  | Qside |  | Qlong |  |
|  | PDC04 | TP | PDC04 | TP | PDC04 | TP |
| pt < 300 | 2.7 | 3.4 | 0.4 | 0.4 | 0.9 | 0.8 |
| 300< pt < 600 | 4.2 | 6.4 | 0.4 | 0.4 | 1.1 | 0.8 |
| 600 < pt  | 6.3 | 11 | 0.6 | 0.5 | 1.3 | 1 |

**Resolution values are very close to the ones in Technical Proposal**
**Improvement in Q****out**** is connected to better p****t**** resolution and higher magnetic field**

## HBT – corrected results 

- pt > 500MeV

**Residual systematics**
**< 0.2 fm**

## Event by Event HBT – pions 

## Photon identification

**PHOS identification:**
**CPV detector: Charged particle rejection.**
**TOF : Rejection of massive low *****p******T***** particles.**
**EMCAL : Hadron rejection via shower topology.**
**Shower topology methods:**
_**Principal component analysis (PCA).**_
**	****3 kinds of ******** defined****:**
****** ****with **_**High Purity**_** - Low Efficiency  (1 standard deviation).**
****** ****with **_**Medium Purity**_** - Efficiency    (2 standard deviations).**
****** ****with **_**Low Purity**_** - High Efficiency  (3 standard deviations).**
_**Shower **__**lateral **__**dispersion**_**.**

## Principal Components Analysis approach

- Shower is described by 7 observables:
- Lateral dispersion
- 1, 2
- Sphericity
- Core energy
- Largest fraction of energy in one cell
- Digit multiplicity
- Signal event sample is used to construct the covariance matrix and a transformation matrix from original observable space to the space of eigen vectors is found (TPrincipal). We assume that background is transformed by the same transformation matrix, and we compare signal and background in the eigen reference system.
- We studied photon identification comparing them with **hadrons** (low energy) and with ******0** (high energy), having two different PCA.

## PCA application for  and 0 recognition

## Identified  spectrum in p-p collisions in 1 ALICE year 

- Spectrum of particles identified as 

- Signal

- Background

_**Background remains too high**_

## Identified  spectrum in Pb-Pb collisions in 1 ALICE year

- Spectrum of particles identified as 

- Signal

_**Background remains too high**_

- Background

## Additional identification of direct  by Isolation Cut Criterion

**Prompt ******** are likely to be produced isolated, with no companion within a cone. ****Prompt ******** can be non-isolated, only if they are produced in next-to-leading order processes (****bremsstrahlung****)****.**** **
**Two parameters define photon isolation**
_**Cone size**_**   **
_***p***__***T***__** **__**threshold**_** : To suppress low *****p******T*****  ****particles from the underlying event****.**

## Direct  spectrum after Isolation Cut in p-p 1 ALICE year

- Spectrum of particles identified as 
- after PID + Isolation cut identification

- Signal

- Background

## Direct  Spectrum After Isolation Cut in Pb-Pb in 1 ALICE Year

- Spectrum of particles identified as 
- after PID + Isolation cut identification

- Signal

- Background

## Final Identified Spectrum1 Year Statistics

- Particles identified as 

## Charm in pp (D0 → K) Sensitivity to NLO pQCD params

*******s***** = 14 TeV**

**Charm in pp (D****0**** ****→ K********) ****Sensitivity to NLO pQCD params**

**down to p****t**** ~ 0 !**

## D0 → K in pPb Statistical and systematic errors

## A first look at RpPb for D0

**Work on D****+**** ****→**** K******** started**

## Beauty: semi-leptonic decays

**from different sources:**

**Beauty: semi-leptonic decays**
***detection strategy***

*Distributions normalized to the same integral in order to compare their shapes*

## Semi-electronic Beauty detection

**Semi-electronic Beauty detection**
***simulation results***

- Expected statistics (107 Pb-Pb events)

***Signal-to-total ratio and expected statistics in 10******7****** Pb-Pb events***

**p****T ****> 2 GeV/c ,  200 ********< |d****0****| < 600 ********m**

** ****90% purity**
** ****40,000 e from B**

## Estimation of uncertainties on the pT - differential cross section of beauty electrons

***Final B-decay electron p******T****** distribution***

## Extraction of a minimum-pT-differential cross section for B mesons

***Using UA1 MC method (*), also adopted by ALICE *********

**(*) C. Albajar et al., UA1 Coll., Phys Lett B213 (1988) 405 **** C. Albajar et al., UA1 Coll., Phys Lett B256 (1991) 121 **

-        The B meson cross section per unit of rapidity at midrapidity with *p**T**B** > p**T**min* is obtained from a scaling of the electron-level cross section measured within a given electron phase space e

-          The semi-electronic B.R. is included here

- The phase space used is			where *p**T* are the previously used bins,
-  = [-0.9, 0.9] and *d**0* = [200,600] m

## Extraction of a minimum-pT-differential cross section for B mesons

- E loss calculations:
- N. Amesto, A. Dainese,
- C.A. Salgado, U.A. Wiedemann,
- hep-ph/0501225

## Beauty from muon raw yields

| pt (GeV/c) | 1.5 -  2 | 2 – 2.5 | 2.5 - 3 | 3 - 4 | 4 - 5 | 5 - 6 | 6 - 9 | 9 - 12 | 12 - 15 | 15 - 20 | 20 - 100 |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| N from b | 2.7 10 6   620 | 1.8 10 6  675 | 1.1 10 6  636 | 1.0 10 6  684 | 4 10 5     474 | 1.7 105  326 | 1.3 10 5  294 | 2.1 104  123 | 5 103  60 | 1.8 103  38 | 474  30 |

| M (GeV/c 2) | 0 - 5 | 5 - 20 |
| --- | --- | --- |
| N from bb | 39678  180 | 6314  71 |

**(Very) large statistics is expected**

- Fits with fixed shapes from the Monte Carlo & **beauty amplitude as the only free parameter ****(****next: tray c also free****)**
- Uses **3** different **data samples**

## Centrality dependence of quarkonium yields in ALICE-muon

**cross-sections from R.Vogt in hep-ph/0311048,**
**assumes neither suppression nor enhancement**
** ****J/********: large stat., good sign.**
**     ****(allows much narrower centrality bins)**
** ********’****: small S/B**
** ********: good stat., S/B ****> 1, good sign.**
** ********’****: good stat., S/B > 1, good sign.**
** ********’’****: low statistics**
**similar rates for ******** in the dielectron channel**

**Centrality dependence ****of quarkonium yields in ALICE-muon**

**S.Grigoryan**

## ’/ ratio versus pt (dimuon channel)

**E.Dumonteil & P.Crochet, ALICE-INT-2005-002**

** ****Melting depends on**
** ****resonance formation time, dissociation temp. & p****t**
** ****QGP temp., lifetime & size**
** ****Ratio is flat in pp (CDF)**
** ****Deviation from the pp (pA) value may be interpreted as an evidence for the QGP (****if we assume the same nuclear absorption for ******** and ********’****)**
** ****The p****t**** dependence of the ratio is sensitive to the characteristics of the QGP**

**J.P.Blaizot & J.Y.Ollitrault, Phys. Lett. B 199(1987)499; F.Karsch & H.Satz, Z. Phys. C 51(1991)209; J.F.Gunion & R.Vogt, Nucl. Phys. B 492(1997)301**

** ****full & realistic simulation**
** ****error bars = 1 month of central PbPb (10%)**

##  to bb

- Statistics: one month PbPb
- Statistics of the reference is in      5  M  20 GeV/c **2** ****** ****5 times larger than that of the probe**
- Errors dominated by uncertainties on ****** nuclear absorption (********20%)**
- Systematic errors underway

**R. Guernane 2004**

**P. Crochet Hirschegg 05**

## Semi-electronic Beauty detection + X

**Semi-electronic Beauty detection + X**
***p******T****** quark distribution***

***Analysis of the electron p******T****** distribution useful for beauty production cross section measurement. But,****** ******what about the quark p******T****** distribution?***

**Under study B ****→ e X and use**
**charged particle in X with displaced vertex – b jet tagging**

## W in pp and  PbPb Collisions

**PbPb 5.5 TeV**

**W********→********Pythia Generation Results**

|  | BR·W(nb) | Nw (run)  | N (Acceptance/run) |
| --- | --- | --- | --- |
| pp 14 TeV | 17. | 340000 |  50000 (14%) |
| PbPb 5.5 TeV | 5.8 | 133000 |  13000 (10%) |

## Jet reconstruction – under study

**Jets are produced copiously**

**Underlying event fluctuations**
**Single particle spectra**
**Correlation studies**

**Event-by-event well**
**distinguished objects**
**Reconstructed jets**

| ET threshold | Njets |
| --- | --- |
| 50 GeV | 2  107 |
| 100 GeV | 6  105 |
| 150 GeV | 1.2  105 |
| 200 GeV | 2.0  104 |

## Intrinsic limit on jet energy resolution

**For R < 0.3:**
*******E/E***** =****	****16% from Background **
**	****(conservative d*****N*****/d*****y***** = 5000)**
**	**
**	****14% from out-of-cone fluctuations**

## Jet structure observables at the LHC

**How close can we get to  the ideal case **
**Measure unquenched parton energy by measuring the jet energy. **
**Determine energy loss and transverse heating by measuring the fragmentation function and *****k*****T**** spectra.**

## Limit experimental bias ... 

**By measuring the jet profile inclusively.**
**Low-*****p*****T**** capabilities are important since for quenched jets sizeable fraction of energy will be carried by particles with *****p*****T**** < 2 GeV.**
**Exploit ********-jet correlation**
***E********* = *****E*****jet**
**Caveat: limited statistics**
******(10****3****) smaller than jet production**
**Does the decreased systematic error compensate the increased statistical error ?**
**Certainly important in the intermediate energy region 20 < *****E*****T**** < 50 GeV.**

- Energy radiated outside core

- Not visible after
*p*T-cut.

- Quenched (AliPythia)
- Quenched (Pyquen)

## Jet structure observables: kT

**Unmodified jets characterized by <*****k*****T****> = 600 MeV ~ const(*****R*****).**
**Partonic energy loss alone would lead to no effect or even a decrease of  <*****k*****T****>.**
**Transverse heating is an important signal on its own.**
**Relation between *****R***** and formation time of hard final state radiation.**
**Early emitted final state radiation will also suffer energy loss.**
**Watch for *****R***** – dependence of <*****k*****T****> !**

## Prompt  spectrum (1 year running)

## Fragmentation functions:  jet

## Physics Performance Report

**Volume 1 ****   ******
**Chapter 1:  ALICE physics – theoretical overview**
**Chapter 2:  LHC experimental condition**
**Chapter 3:  Alice detector**
**Chapter 4: Offline computing and Monte Carlo generators**
**published as special issue of Journal of Physics G, volume 30(11) (November 2004) pp 1517 – 1763 **
**among top 3% most downloaded articles across all IOP journals**
**editors eagerly waiting for volume two...**
**Volume 2****    ******
**coming ... **

-  ****** ****published**
-  ******    ****ready**
** ********       ****nearly ready**
-  ******          ****advanced**
-  ******             ****started**

## Physics Performance Report

**Chapter 5:  Reconstruction Performance  **** **********
***(contains the description from raw data to ESD)***
**Tracking Performance                                         **** **********
**writing has to be completed, muon tracking ready**
**Vertexing - primary and secondary vertices****      **********
**small update on kinks**
**HLT tracking                                                          **********
**draft text prepared**
**Charged Particle Identification****                            ******
**update on TOF and HMPID, combined PID done**
**Photon Identification****                                             ******
**prepared**

## Physics Performance Report

**Chapter 6:  Physics Performance****                ******
**Event Characterization****                                         **********
**Particle Production****                                               ******
**Particle Correlations****                                             **********
**Flow****                                                                        ******
**Charm and Beauty Physics****                                 ******
**Quarkonia Production****                                          ******
**Photon Physics****                                                     **********
**Event-by-Event Physics****                                       **********
**Jet quenching****                                                        **********
**Cosmic physics                                                     ******
**Ultra-peripheral collisions                                    **********

***On critical path***

## Physics data challenge ‘04

## Signal production for PDC

## Plans with PDC data

**Delay in analysis due  to availability of the tools for distributed analysis**
**gLite release postponed**
**we are trying to get out lightweight system workonig**
**ALIEN/gShell**
**in the mean time we analyzed ‘by hand’ the copy of data at CERN (HBT analysis, partly jets)**
**we define two examples to be run now with ****ALIEN/gShell**
**Omega production (on all ‘underlying events’)**
**jet reconstruction on signal implemented in events**
**‘****crash programme’ for jet analysis – **
**shrink the data to fit (few) disk**
**use standard (non-distributed) analysis tools**

## Organization

**to coordinate the development of analysis **
**to prepare initial running scenario for ALICE**
**We have established Physics Working Group**
**detector performance group (convener Yu.Belikov)**
**overall detector performance, tracking, vertexing, PID**
**soft physics (conveners Ch.Kuhn, L.Ramello)**
**initially very large group (event characterization, particle production, strangeness, HBT – particle correlation, flow, event-by-event physics**
**heavy-flavour physics (conveners F.Antinori, G.Martinez)**
**covering both open heavy-flavour and quarkonia production**
**high-pt and photon physics (conveners A.Morsch, Y.Schutz)**
**include high-pt phenomena study (jet quenching), and photon (both thermal and high-pt photons)**

## Organization

**Physics working group conveners together with Physics coordinator and deputy consist Physics Board**
**Physics Board meets ones per month**
**it’s attended by spokesperson and his deputies**
**Physics coordinator reports about progress on each Management Board**
**Former Editorial Board (responsible for PPR) was integrated with PB**
**Until publishing PPR the EB chair (G.Paic) is invited to PB**
**Physics group conveners coordinate corresponding sections of chapter 6**
**section editors report to Physics group conveners**
**they report to EB chair and Physics coordinator**

## Planning

**First task PPR volume 2**
**assemble text and figures till July 1****st**** 2005**
**editing, preparation till October 2005**
**published before the end of 2005 **
**Year 2006**
**understanding of calibration and alignment**
**analysis tools**
**preparation of running programme**
**Year 2007**
**final tests**

## First physics programme

**ALICE will start with pp running**
**luminosity at start estimated at 10****29****cm****-2****s****-1**** or lower**
**practically no pile up in TPC (the slowest detector) – golden time for ALICE pp physics**
**first pp data**
**charged particle multiplicity, multiplicity distribution**
**transverse momentum spectra**
**momentum multiplicity correlation (meant p****t**** as a function of multiplicity)**
**later**
**strangeness production, identified particle spectra (needs more calibration)**
**First results in Pb-Pb**
**we expect first exploratory run (few days)**
**charged particle multiplicity**
**elliptic flow (no need for detailed corrections)**
**transverse momentum spectra**