Study of charm hadroproduction & T au neutrino production at CERN SPS

1. 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 A. Murat GÜLER@METU

2. 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.. A. Murat GÜLER@METU

3. Concept of ντDetection ντ ντ detection ντ τ X Proton beam ντ production ντ detection: • Statistical uncertainty 33% in DONUT. ντ Primary proton X Ds τ ντ D+ 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 X' A. Murat GÜLER@METU

4. DONuT Experiment 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) transverse dependence longitudinal dependence 9 ντ CC events observed A. Murat GÜLER@METU

5. DsTau Experiment • Emulsion based experiment @ CERN SPS • Precise mesurement of ντ CC cross section • Aiming to detect 103 Dsτ 0.05 A. Murat GÜLER@METU

6. Emulsion detectors AgBr crystal 1014crystals in a film Highest position resolution Emulsion film Cross-sectional view Emulsion layer (44 m) Plastic base (200 m) 200 nm Emulsion layer (44 m) 3D tracking device Sensitivity36 grains/100 m 10GeV/c  beam 20 m A. Murat GÜLER@METU

7. High precision measurement Piezo objective scanner σx = 50nm θ 200 μm base Position reproducibility ~ 8 nm Angular reproducibility ~ 0.15 mrad Beam angle • 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 A. Murat GÜLER@METU

8. 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

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

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

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

12. Expected Performace 2018 run 2021 run Uncertainties Aiming at 10%precision to look for new physics effects in ντ-nucleon CC interactions 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 A. Murat GÜLER@METU

13. DsTau Collaboration Japan: Nagoya Kyusyu Aichi Kobe Status of the project Switzerland: Bern Romania: Bucharest Russia: Dubna Turkey: Ankara • 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 A. Murat GÜLER@METU

14. Beam Exposure schedule A. Murat GÜLER@METU

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

16. Automatic Scanning Microscope • A fast scanning in Nagoya Univ. • Scanning speed of 22 m2/day • Precision measurementinBern • 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) A. Murat GÜLER@METU

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

18. Efficiency of Ds detection MC with 400GeV beam FLt t qX Proton Ds qt X FLDs A. Murat GÜLER@METU

19. 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 Tungsten target A. Murat GÜLER@METU

20. 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 200 μm 1000 μm A. Murat GÜLER@METU

21. 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 100 μm

22. 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 charmproduction) • Test experiments conducted in 2016-2017 • Pilot run in 2018 and physics run from 2021 A. Murat GÜLER@METU

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

24. 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 describingdσ(Ds)/dxF ~(1-|xF|)n • No experimental data giving n for Ds A. Murat GÜLER@METU