Calorimeter Object Status. A&S week, Feb M. Chefdeville, LAPP, Annecy

Transcription

1 Calorimeter Object Status St A&S week, Feb M. Chefdeville, LAPP, Annecy

2 Outline Status of Pi0 calibration Calibration survey with electrons (E/p) Calorimeter performance with single photons from charm decays Status of migration of neutral PID-lines to Turbo-Calib Lists of open tasks Aknowledgments : part of the material from Jean-Francois, Marie-Noelle & Zhirui Xu 2

3 Status of π0 calibration Last calibration performed in May Since then, PMT gain auto-corrections based on LED monitoring keep the mass peak roughly constant in the 3 ECAL regions. On-going work focuses on understanding the residual shift and the small difference between regions and improving the fit stability & speed. Possibly originates from a lack of information in the fmdst. 3

4 Issue with femto-dst Online calibration goes as follows : MDF file Run on MDF files and produce fmdst and Ntuples; Ntuples are used as starting point for the first 7 iterations fmdst -> calculate the correction factors λ for the 6016 ECAL cells; The factors are used as input for a reconstruction based on fmdst clusters -> new Ntuples are produced Ntuples Another 7 iterations give the factors used to correct the HVs While investigating energy corrections, it was found that : Ecluster(Ntuples) Ecluster(fmDST) with percent level differences. In fact : Ntuple clusters are 3x3 cells while during the reconstruction, the CaloShowerOverlap tool modifies the cluster energy, accounting for energy sharing up to 4 cells away from the considered cluster. 4

5 Effect on the cluster energy First correction factors (λ) are obtained from clusters including energy sharing and are applied on clusters without any possible sharing. -> Almost impossible to get the setpoint value after applying the computed λ. Code modified to keep more cells around the cluters (fmdst size : +60 %). Difference when keeping 3x3 and 9x9 cells around the seed (fmdst - Ntuples) / fmdst Effect reduced from 4 % to 0.4 % 5

6 Effect in different regions Energy sharing dependent on occupancy -> Effect larger in inner region. May explain why we always noticed π0 mass differences between inner, middle and outer regions. Other checks also ongoing on the selection (increase stat. around the beam pipe) 6

7 Fit method In general, the current calibration is okay, except in certain regions Inner region, cells around the beampipe, high statistics but no π0 mass peaks; Low statistics in the cells along x-axis, close to y=0 for all three regions; Outer region, cells at the edges with low statistics. Middle region is in general better than the Outer and Inner regions. But new calib. methods required around the beampipe and in low-stat regions. 7

8 Calibration survey with electrons Look at per-cell variations of Means & Sigmas of the gaussian fit to E/p. Comparison between Run2 & Run1 DiMu DST : 2012, 2015 (October) & 2016 (May-June, July-Aug.) Performed using Di-electrons tracks Tag electron with PID requirement + Probe electron E/p Require 1500 candidates per cell, cut on the fit chi2 8

9 E/p distributions in Inner Middle Outer Mean Sigma

10 Difference E/p : & Δ(E/p) Inner Middle Outer % -2.2 % -2.4 % % -3.2 % -3.7 % A small shift is observed More pronounced in the horiz. plane crossing the beam These findings correlates well with the factors from the π0 calibration. E/p(2016)-E/p(2012) λ VS E/p(2016) 10

11 Interest in single-photon decays 2-fold : Calibration of neutral PID & check energy calibration IsPhoton = high-pt photons (> 2 GeV/c) VS merged π0, tool for run1 (K*γ, Kππ0) IsNotH = photons VS hadronic background, no tool yet, adapt isphoton one. Need to extend photon PT range down to 200 MeV/c -> single-photon decays IsNotE = photons VS EM bkg. > not clear where this is needed PS : PID lines will move to Turcal in 2017 (see later) Bs Φ γ (Run1) IsPhoton Before/after MC resampling Photons from resolved π0 - J/Ψ K*+ (Run1) Data MC 11

12 Single-photon lines Soft photons (PT_min = 400 MeV) Ds*+[ Ds+[KKπ] γ ] -> Thanks to Anton Poluektov Stripping lines for Ds+ [FULLDST], photon added offline : S21 : CharmCompleteEvent/Phys/D2hhhControl_KKPLine S24 : CharmCompleteEvent/Phys/StrippingD2hhhFTCalib_KKPLine S26 : CharmCompleteEvent/Phys/StrippingD2hhhFTCalib_KKPLine 0.03 prescale 0.2 prescale 0.2 prescale Intermediate-PT photons (PT_min = 1 GeV) Ds+[ η'[ππγ] π+ ] (> 1 GeV) -> Thanks to Simone Stracka Stripping lines for D+ & Ds+ [MDST]: S21 : Charm/Phys/StrippingD2PiPi0_eegammaPiEtaPrimePromptLine S24 : Charm/StrippingD2EtaPrimeHD2PiEtaPrimePPGLine S26 : Charm/StrippingD2EtaPrimeHD2PiEtaPrimePPGLine For 2015 & 2016, some HLT2 lines already exists no prescale no prescale no prescale High-PT photons (PT_min = 3 GeV), Bd [K* γ], not discussed here Available : Ntuples with small set of variables for periods When we have a good understanding of yield & purity : -> Ntuples with large set of variables (all CaloHypos), CaloObject storage on eos. 12

13 Additional lines, PT range (MC) Right plot : 2012 calib. sample of K*γ (25x103) & photons from D*[π0] (4.3x106) Ds*+[ Ds+[KKπ] γ ] DecFile : (link), 2012, Pythia6&8, ~2x106 events PS : in stripping, PT > 200 MeV (StdAllLoosePhoton), increased to 400 to manage combi. Ds+[ η'[ππγ] π+ ] DecFile : (link), 2012, Pythia8, ~1.5x105 events PS : in stripping, PT > 1 GeV 13

14 First fits Year N(Ds*+) / 103 N(D(s)+) / x x Ds* Big & clean! PS : no cut on the γ CL (PID sample). Window of 20 MeV/c2 around η mass D(s)

15 From PID to performance control η for D candidates within 3-σ of their nominal masses Large sample of η in 2016 (looks like ~ 900 x 103 candidates) Study of energy calibration dependence on several variables η

16 Mass peak in different ECAL regions In Run 2, Ds*+ and η 1-2 MeV/c2 from PDG-value Peak width is also very stable between different periods (Year/Mag) Best resolution is found in the middle region Ds*+(fitted μ & σ) η (fitted μ & σ) 16

17 Effect of cluster isolation A suitable variable is the χ2 value of the cluster & track matching Good ground for testing the energy corrections (overlap, pile-up) A B A C B C D D 17

18 Effect of cluster isolation Effect of corrections seen as an increase of peak low isolation Decreasing trend of the peak position : corrections have room for improvements Effect of other variables being studied (PT, PRS energy...) A B C D 18

19 Migration of neutral lines to TURCAL TURCAL = TURBO CALIB stream = Turbo with Calo raw banks Have similar workflow for charged & neutral PID calibration : Data quickly available through central production : fast feedback to spot problems in HLT Integration into WGProduction (= histos, sweights, Ntuples) is a proposed taks of PID&Co (see next slide) Code commited for the 4 lines (Carla K*γ, Regis Kππ0, Max Ds*+ & D(s)+) MC production just started. Will be used to assess the rates & tune the cuts 19

20 Calo-object task list If you wish to participate to some calo-related software development : Development of a calibration tool for photon PID variables (isnoth, isnote) Performance of DTF for decays with merged π0 Reconstruction of photons converted in the Velo Pile-up subtraction in the Calorimeter cluster reconstruction MC validation of calo-related variables Please see backup slides for more details. + some submitted by PID&Co : Integration of the neutral lines in the WGP Integration of neutral PID-tools into PIDCalib 20

21 Outlook Pi0 calibration accuracy at the percent level, significant progress with understanding the current limitations + on-going development on the fit. Control of calorimeter performance in Run 2 well on-going : Electrons, pi0, control modes with single photons Mass peaks at the right place for low-pt & medium-pt photon modes Neutral PID will benefit from several developments New lines, higher rates (stripping to trigger), WGP, new calibration tools Help is welcome, feel free to contact Miriam or myself to contribute. 21

22 Calo Object task list Title: "Development of a calibration tool for photon PID variables (isnoth and isnote)" Description: Produce dedicated calibration samples of low energy photons (data and MC) and extract signal candidates using splot techniques. Adapt the calibration tool that already exists for the PID variable isphoton to the variables isnoth and isnote. Duration: 3 months 30% FTE. Pre-knowledge: Root/Roofit at the basic level, Python and DaVinci TupleTools. Title: "Performance of DTF for decays with merged pi0" Description: For decays with a merged pi0, applying a constraint on the pi0 mass with DecayTreeFitter (DTF) does not give any improvement on the B mass. This might be related to the cov. matrix for merged pi0, which could be improved. To be further investigated. Duration: 3 months 30% FTE. Pre-knowledge: DTF usage, C++ Title: "Reconstruction of photons converted in the Velo" Description: Continue the studies related to tracking that lead to improvements on the reconstruction of early converted photons. Preliminar results presented at: Duration: 4 months 30% FTE. Pre-knowledge: C++, python Title: "Pile-up subtraction in the Calorimeter cluster reconstruction" Description: The current pile-up subtraction in the cluster reconstruction is done as function of the global SPD multiplicity. However, it seems that the pile-up level is channel-dependent. This pile-up subtraction could be improved by using a local occupancy, e.g. the number of track or SPD hits in a given cone around the neutral object. Duration: 3 months 30% FTE. Pre-knowledge: C++, python Title: "Calo MC validation" Description: "Revisit the set of calo histograms used to check the simulation quality. Check the SimCond is up-to-date and propagate what is done in the data reconstruction. Some conditions in SimCond use the same parameters as in real data CondDB, but some of them probably need to be adapted for MC (E/S/L-correction parameters). " Duration: 4 months 30% FTE. Pre-knowledge: CondDB, C++, python 22