Study of charm hadroproduction Tau neutrino production at CERN SPS BEACH2018 The XIII International Conference on Beauty, Charm and Hyperon Hadrons Peniche, Portugal Study of charm hadroproduction & Tau neutrino production at CERN SPS A.Murat GÜLER METU Ankara On behalf of the DsTau Collaboration 4/7/2019 A. Murat GÜLER@METU

Physics Motivations Tau neutrinos are the least known particle in the Standard Model. Testing the lepton universality in ντ CC cross section ντ cross section was measured with a large uncertainty Important for future neutrino experiments, SHiP, DUNE, Hyper-K.. 4/7/2019 A. Murat GÜLER@METU

Concept of ντ Detection Proton beam τ ντ X ντ production ντ detection: Statistical uncertainty 33% in DONUT. D+ Ds τ ντ X X' Primary proton Main ντ source: Ds →  decays produced in proton interactions  No experimental data on differential cross section of Ds  Large systematic uncertainty (~50%) in the ντ flux prediction 4/7/2019 A. Murat GÜLER@METU

DONuT Experiment 9 ντ CC events observed ντ CC cross section   where n is the parameter controlling the longitudinal part of the Ds differential cross section “Final tau-neutrino results from the DONuT experiment”, Physical Review D 78, 5 (2008) longitudinal dependence transverse dependence 4/7/2019 A. Murat GÜLER@METU

DsTau Experiment Emulsion based experiment @ CERN SPS Precise mesurement of ντ CC cross section Aiming to detect 103 Dsτ Systematic uncertainties DONuT DsTau Ds differential cross section (xF dependence) ~0.5 0.1 Charm production cross section 0.17 Decay branching ratio 0.23 Target atomic mass effects (A dependence) 0.14 0.05 4/7/2019 A. Murat GÜLER@METU

Emulsion detectors Highest position resolution AgBr crystal 1014 crystals in a film Highest position resolution Emulsion film Cross-sectional view Emulsion layer (44 m) Plastic base (200 m) Emulsion layer (44 m) 200 nm 20 m 10GeV/c  beam Sensitivity 36 grains/100 m 3D tracking device 4/7/2019 A. Murat GÜLER@METU

High precision measurement Intrinsic resolution of each grain = 50 nm Two grains on top and bottom of 200 mm base  0.35 mrad Discrimination of 2 mrad at 4σ level A new system with piezo-based Z axis under development Angular measurement reproducibility of 0.15 mrad was achieved Piezo objective scanner Position reproducibility ~ 8 nm Angular reproducibility ~ 0.15 mrad θ σx = 50nm 200 μm base Beam angle 4/7/2019 A. Murat GÜLER@METU

A pion Interaction in Emulsion 3D Vector information, position and slope . Tracking by 35 nm position resolution. m.i.p and nuclear fragment is easily distinguished

Detector Structure 400 ECCs will be exposed to accumulate 2.3x108 interactions 10 units (total 100 emulsion films) ECC for momentum measurement (26 emulsion films interleaved with 1 mm thick lead plates) Proton Ds τ X D+ X’ Tungsten / molybdenum 4/7/2019 A. Murat GÜLER@METU

Detection of Ds → τ → X event Kink angle of Ds The analysis chain: 1) Tag X decay (mean ~100 mrad) 2) Perform high precision measurement to detect Ds decay <θ> 7 mrad Need high precision measurement! Flight length of Ds <FL> = 3.3 mm Flight length of τ <FL>=2.0 mm 4/7/2019 A. Murat GÜLER@METU

Ds momentum reconstruction Difficult to measure Ds momentum directly due to short lifetime Artificial Neural Network (ANN) using 4 variables Ds τ Primary proton FLDs FL τ Δθ Ds → τ FL: flight length Δθ: kink angle Δθ τ →X Measure xFdistribution Δp/p= 18% Fit to (1-|xF|)n n = 5.8 4/7/2019 A. Murat GÜLER@METU

Expected Performace Relative systematic uncertainty for cross section measurement: ~30% with 2018 run  Re-evaluation of the DONUT result ~10% with 2021-2022 run  Input for future measurement 2018 run 2021 run Uncertainties Aiming at 10% precision to look for new physics effects in ντ -nucleon CC interactions 4/7/2019 A. Murat GÜLER@METU

DsTau Collaboration Status of the project Japan: Nagoya Kyusyu Aichi Romania: Bucharest Russia: Dubna Turkey: Ankara Switzerland: Bern Japan: Nagoya Kyusyu Aichi Kobe Letter of Intent Submitted to the CERN-SPSC in Feb. 2016 Test Beam Studies in November 2016 and May 2017 Physics runs : 2018, 2021-2022 4/7/2019 A. Murat GÜLER@METU

Beam Exposure schedule Run Beam time Emulsion surface Goal 2016 test beam (10 modules) Test of the setup Proof of principle 2017 test beam (~2 modules) Improvement of exposure scheme pilot run (approved) 1 week 48 m2 (30 modules) Test of large data taking and analysis BG estimation with data Physics results (~80 Ds →  detected) 2021 physics run (recommended) 2 weeks 545 m2 (338 modules) Physics results (~1000 Ds →  detected) 2022 physics run 4/7/2019 A. Murat GÜLER@METU

Test Beam @ CERN H4 beam line Target mover ECC Stage controled By each spill Proton Silicon detector 4/7/2019 A. Murat GÜLER@METU

Automatic Scanning Microscope A fast scanning in Nagoya Univ. Scanning speed of 22 m2/day Precision measurement in Bern Resolution ~0.3 mrad Hyper Track Selector (HTS) System 2. Precision measurement to detect Ds  τ decay (a few mrad) High speed scanning of full area to select τ  X + partner-charm decays (Δθ ~100 mrad) 4/7/2019 A. Murat GÜLER@METU

Automatic Scanning Microscope ~4000 tracks in 2 x 2 mm2, 15 films 1000 μm 4/7/2019 A. Murat GÜLER@METU

Efficiency of Ds detection X qX FLDs FLt qt Proton MC with 400 GeV beam Selection Total efficiency (%) (1) Flight length of Ds ≥ 2 emulsion layers 77 (2) Flight length of  ≥ 2 layers & Δθ(Ds) ≥ 2 mrad 43 (3) Flight length of Ds < 5 mm & flight length of  < 5 mm 31 (4) Δθ() ≥ 15mrad 28 (5) Pair charm: 0.1 mm < flight length < 5 mm (charged decays with Δθ > 15 mrad or neutral decays) 20 4/7/2019 A. Murat GÜLER@METU

Z distribution of observed vertices Interactions in a tungsten plate Event reconstruction Measured proton beam density in the analyzed region: 4.36x105 beam tracks/3.61 cm2 Z distribution of observed vertices Interactions in a tungsten plate 200 μm # of vertices Expected 1860 Observed With parent 1832 Without parent 130 Tungsten target 4/7/2019 A. Murat GÜLER@METU

Reconstructed Double vertex Kink IP of daughter 291.6 μm FL 2536.6 μm kink angle 118 mrad Vee IP of daughters 20.9, 109.7 μm FL 554.5 μm opening angle 242 mrad 1000 μm 200 μm 4/7/2019 A. Murat GÜLER@METU

Double-decay topology event (open charm) (Video in ppt) Kink IP of daughter 291.6 μm FL 2536.6 μm kink angle 118 mrad Vee IP of daughters 20.9, 109.7 μm FL 554.5 μm opening angle 242 mrad N1ry 40本以上 100 μm

Summary The DsTau project is proposed to measure ντ production (Ds differential production cross section) reduce systematic uncertainty in the cross section measurement to 10% Emulsion detectors with nano-precision readout About 1,000 Ds →  decays in 2.3×108 proton interactions will be detected. By-product: study charm physics (~105 charm production) Test experiments conducted in 2016-2017 Pilot run in 2018 and physics run from 2021 4/7/2019 A. Murat GÜLER@METU

Physics Motivations Charmed hadron interaction cross section measurement D+ X To be sure requesting daughter as electron D- X’ D+ 4/7/2019 A. Murat GÜLER@METU

Physics Motivations Precise mesurement of in ντ CC cross section reduce uncertainity to 10% ντ : only the DONuT experiment Measured as a function of a parameter n describing dσ(Ds)/dxF ~(1-|xF|)n No experimental data giving n for Ds 4/7/2019 A. Murat GÜLER@METU