Non-oscillation physics Report of the WG M. Sioli, OPERA Collaboration Meeting, Mizunami, 21/01/2009

Activities in the WG Atmospheric muon charge ratio  See later Atmospheric upgoing neutrino induced muons  See later Coincidences between LNGS experiments  See later Measurement of neutrino velocity with the CNGS beam  No news w.r.t. Sorrento (remember WFD problem in the CERN DB) Neutral heavy lepton searches  Still no candidates (persons!)

Atmospheric muon spectrum and charge ratio (N. Mauri and M. S.) Different selection levels:  Selection of good-quality extractions: based on distribution of  event rate AND nTT AND nRPC AND nHPT1 AND nHPT2 AND nHPT3 AND nHPT4 AND nHPT5 AND nHPT6  After this first selection: corresponding livetime: 88 days  Total number of events:  Charge and momentum reconstructed events: Excellent cross check between MACRO and OPERA data: Ratio REAL/MC = (97.3 ± 0.5)%  Selection of good-quality events:  cut on the number of clusters, on the fraction of used clusters for each track, on parallelism condition for bundles  Selection of good-quality tracks:  cut on the maximum number of HPT digits per station

Inverted magnet polarity data (IP): from 3 rd until 12 th November (Extractions #953  #971) Different selection levels:  Selection of good-quality extractions: livetime: 9.0 days  Total number of events:  Charge and momentum reconstructed events: 9309 Ratio Rate SP /Rate IP = (102.7 ± 1.0)%  Selection on good quality tracks:  cut on the maximum number of HPT digits per station  Only Magnet 2 was on (Magnet 1 off since Extraction #955): only SM2 events have been analyzed.  Charge and momentum reconstructed events in SM2: 2447 (after cuts)

Momentum measurement 1 SM 2 SM MC rec REAL data MC truth GeV/c log10(P/GeV/c)

Atmospheric muon charge-ratio The update of cosmic ray muon analysis using data collected with standard and inverted magnet polarity let us investigate the charge ratio as a function of different variables.  Studying the charge ratio as a function of the azimuthal angle we found a huge source of systematic error on the charge-reconstructed data (already presented in Sorrento)

Presented at Physics and Analysis Meeting in Sorrento: Charge ratio as a function of the azimuthal angle SM1 vs SM2 - HPT doublets SM1 = 180 o SM2 = ~210 o azimuth angle (degrees)

Reconstructed muon charge ratio Muon charge ratio as a function of the azimuth angle in the 4 magnet arms

Conjecture assumed: ambiguity in HPT reconstruction 150 o 210 o Directions in which we found the major effects in the CR modulation

Study of the conjecture We selected a set of events (~150) in the direction with the major effect on CR (210 deg), and looked by eye at the HPT fit reconstruction: we found only 10% badly reconstructed events, we could remove using a cut on the sigma of the reconstructed angle. Example of a typical event (good behavior of the HPT fit algorithm)

Study of the conjecture 10% badly reconstructed events: an example

Misalignment effect Interpretation of this effect is misalignment in xz-direction: we disentangled the x-contribution from the z-contribution. The x-shift of one HPT station w.r.t the other one corresponds to the x-residual in the nearly horizontal direction, while the S-shape is due to a z-shift. We corrected the “relative” position of the second station w.r.t the first station in the doublet. We corrected the x-shift, using the shift around the horizontal direction, and then the z-shift, minimizing the slope of the residual distribution w.r.t the reconstructed angle (we expect a flat distribution around 0).

Further studies We investigated other sources for this effect running OpRec with DTubeReconstruction only on singletts, i.e. forcing the reconstruction only in each HPT station. We studied the x-residuals, the x difference between two stations in each doublett at an average z.  x = x HPT1 – x HPT2 angle HPT2 (cm)

Misalignment correction Residuals projected on the distance between the 2 HPT fit

Corrections applied after the doublet alignment X correction (cm)Z correction (cm) Plane2_SM Plane4_SM Plane6_SM Plane2_SM Plane4_SM Plane6_SM Corrections (in cm) we applied to the  x and  z shifts in the alignment files in OpUtils/v*/data/DriftTube/Alignment

After corrections Residuals projected on the distance between the 2 HPT fit

Effect on the reconstructed muon charge ratio Muon charge ratio as a function of the azimuth angle with the standard alignment files

Effect on the reconstructed muon charge ratio Muon charge ratio as a function of the azimuth angle with the corrected alignment files

Other possible effects to be investigated 1) Most probably we have to implement other iterations to converge 2) There could be bending effects on the X direction that could produce such a shape x z

Overall charge ratio (SM1+SM2) Muon charge ratio as a function of the azimuth angle with the corrected alignment files. CR = ± Cuts: (1 <  < 50) mrad

Further corrections: same process for extractions with magnet off In this case the residuals are calculated between HPT doubletts (DTubeReco on both HPT stations). 1 st arm 4 th arm3 rd arm 2 nd arm It seems (of course) better than the singlett case, but… At a more narrow scale, we could think to correct for at least  x shift (recognizable around horizontal direction, i.e. 0 deg)

Delta-angle with magnet off  for extractions with magnet off, after the corrections on the Alignment files

Variation of CR w.r.t  cut CR (fit) CR (fit corrected with misid) (0 <  < 50) mrad ± (1 <  < 50) mrad ± (2 <  < 50) mrad ± (5 <  < 50) mrad 1.28 ± Charge ratio prediction: 1.31 ± 0.02 stat ± 0.01 comp-model Absolute normalization: OPERA/FLUKA = (0.96 ± 0.03) FLUKA PREDICTIONS

Atmospheric upgoing neutrino induced muons (Timothee B, Jacques M.) Reprocessing of all the data with the new CosmicPattern version and into a 64 bit architecture. Important also to test the new version of the reconstruction code, which is going to be published on CVS.

Coincidences between LNGS experiments This new topic is going to be started  Involved people: Dario A. and M. S. for OPERA M. Selvi (INFN-Bologna) for LVD Other interested people are warmly welcomed (Olga R. has been contacted)  Work already done: M. Selvi prepared a file in which he selected July events with timestamp and event number, ready to be cross-referenced with a similar file from the OPERA side MC simulation: FLUKA simulation has been extended in order to include hall A, B and C (from a CAD file) and the OPERA, LVD and ICARUS volumes, to be used by the corresponding Collaborations to feed their detector simulation package.

Conclusions In the NOP WG, some analysis are in a good state, most of the problems have been solved (upgoing muon analysis) or are on the way to be solved (  charge ratio) A new study is going to be started (OPERA-LVD coincidences) The paper on the charge ratio measurement has been stopped up to the complete solving of the alignment problem: what we need is the “state of the art” of HPT data analysis (correct timing cuts, last alignment files...)

Spares

MC charge mis-assign as a function of azimuthal angle HPT SingletsHPT Doublets azimuth angle (degrees)