SEARCH FOR HIGHLY IONIZING PARTICLES WITH THE PIXEL DETECTOR AT - PowerPoint PPT Presentation

� 1 SEARCH FOR HIGHLY IONIZING PARTICLES WITH THE PIXEL DETECTOR AT BELLE II Katharina Dort, Soeren Lange, Klemens Lautenbach (katharina.dort@physik.uni-giessen.de) International Workshop on e+e- collisions from Phi to Psi 28/02/2019

WHAT ARE HIGHLY IONIZING PARTICLES? � 2 PHIPSI19 NOVOSIBIRSK KATHARINA DORT, UNIV. OF GIESSEN

HIGHLY IONIZING PARTICLES = particles with a characteristically high energy loss • Examples: • Anti-Deuterons •Magnetic Monopoles • Monopoles appear in various theories ('t Hooft, GUT, String Theories etc.) •Monopoles arising from Dirac Quantization Theory : eg = n ℏ c ≈ 68.5 e ⋅ n 2 Paul A. Dirac, Proc. R. Soc. Lond. A, 133, 60-72 (1931) G. Lazarides et al., Phys. Rev. Lett., 49, 1756 (1982) � 3 PHIPSI19 NOVOSIBIRSK KATHARINA DORT, UNIV. OF GIESSEN

CHARACTERISTICS OF MAGNETIC MONOPOLES Non-Bethe-Bloch energy loss Trajectory in magnetic field Beryllium d E /d x mpl ≈ β 2 ⋅ d E /d x Bethe − Bloch ➡ See Dark Sector physics at Belle II at XXXIX International Conference on High Energy Physics by Dmitrii Neverov � 4 PHIPSI19 NOVOSIBIRSK KATHARINA DORT, UNIV. OF GIESSEN

WHAT SEARCH STRATEGY IS PURSUED? � 5 PHIPSI19 NOVOSIBIRSK KATHARINA DORT, UNIV. OF GIESSEN

PAST SEARCHES The MoEDAL Experiment •Most searches performed with Nuclear Track Detectors (NTDs) •Searches at electron-positron colliders: •MODAL at LEP : NTDs J. L. Pinfold, et al. Phys. Lett. B 316, 407 (1993) •TRISTAN at KEK : NTDs K. Kinoshita et al., Phys. Lett. B 228, 543 (1989) •CLEO at CESR : NTDs T. Gentile et al. [CLEO Collaboration], Phys. Rev. D 35, 1081 (1987). •PETRA at DESY : NTDs P. Musset, M. Price and E. Lohrmann, Phys. Lett. 128B, 333 (1983) •TASSO at DESY : Tracking W. Braunschweig et al. [TASSO Collaboration], Z. Phys. C 38, 543 (1988) •OPAL at LEP : Wire Chamber W. Braunschweig et al. [TASSO Collaboration], Z. Phys. C 38, 543 (1988) G. Abbiendi et al. [OPAL Collaboration], Phys. Lett. B 663, 37 (2008) � 6 PHIPSI19 NOVOSIBIRSK KATHARINA DORT, UNIV. OF GIESSEN

SUPER KEKB • Asymmetrical Electron- Positron Collider with center- of-mass energy of 10.58 GeV 40x KEKB peak luminosity: ℒ = 8 ⋅ 10 35 cm − 2 s − 1 � 7 PHIPSI19 NOVOSIBIRSK KATHARINA DORT, UNIV. OF GIESSEN

BELLE II DETECTOR KLong/Muon Detector Vertex Detector Aerogel RICH Central Drift Chamber Electromagnetic More details: Calorimeter Super KEKB and Belle2 status and plans Time-of-Propagation from Prof. Xiaolong Wang Counter � 8 PHIPSI19 NOVOSIBIRSK KATHARINA DORT, UNIV. OF GIESSEN

PIXEL DETECTOR Plan for post-LHC physics? 2 layer DEPFET Pixel Detector (PXD) • R = 1.4 cm / 2.2 cm • Thickness: 75 μ m • Pixel size: 50 μ m - 85 μ m � 9 PHIPSI19 NOVOSIBIRSK KATHARINA DORT, UNIV. OF GIESSEN � 9

PIXEL DETECTOR Plan for post-LHC physics? H i g h s p a i n t i c a l l o r s e t e h s o e p l r i u o n t x t i e o i m r n a i c t t y i o t o n r e g i o n 2 layer DEPFET Pixel Detector (PXD) • R = 1.4 cm / 2.2 cm • Thickness: 75 μ m • Pixel size: 50 μ m - 85 μ m � 10 PHIPSI19 NOVOSIBIRSK KATHARINA DORT, UNIV. OF GIESSEN � 10

PAST SEARCHES The MoEDAL Experiment •Most searches performed with Nuclear Track Detectors (NTDs) Belle II at KEK : •Searches at electron-positron colliders: PXD (+ Tracking) •MODAL at LEP : NTDs J. L. Pinfold, et al. Phys. Lett. B 316, 407 (1993) •TRISTAN at KEK : NTDs K. Kinoshita et al., Phys. Lett. B 228, 543 (1989) •CLEO at CESR : NTDs T. Gentile et al. [CLEO Collaboration], Phys. Rev. D 35, 1081 (1987). •PETRA at DESY : NTDs P. Musset, M. Price and E. Lohrmann, Phys. Lett. 128B, 333 (1983) •TASSO at DESY : Tracking W. Braunschweig et al. [TASSO Collaboration], Z. Phys. C 38, 543 (1988) •OPAL at LEP : Wire Chamber W. Braunschweig et al. [TASSO Collaboration], Z. Phys. C 38, 543 (1988) G. Abbiendi et al. [OPAL Collaboration], Phys. Lett. B 663, 37 (2008) � 11 PHIPSI19 NOVOSIBIRSK KATHARINA DORT, UNIV. OF GIESSEN

PIXEL DETECTOR (PXD) Neural Networks Feed-Forward Networks Unsupervised Training: Self - Organizing Maps Input Variables Cluster size properties + Charge distribution in cluster • Dirac monopoles do not reach outer ——————————————————————— sub-detectors 6-dim input vector • Principal purpose of PXD: Tracking in or close proximity to interaction region 5x5 pixel matrix around cluster •Our objective : Check if particle identification with PXD is feasible � 12 PHIPSI19 NOVOSIBIRSK KATHARINA DORT, UNIV. OF GIESSEN

PIXEL DETECTOR (PXD) Neural Networks Feed-Forward Networks Unsupervised Training: Self - Organizing Maps Input Variables Cluster size properties + Charge distribution in cluster • Dirac monopoles do not reach outer ——————————————————————— sub-detectors 6-dim input vector • Principal purpose of PXD: Tracking in or close proximity to interaction region 5x5 pixel matrix around cluster •Our objective : Check if particle identification with PXD is feasible � 13 PHIPSI19 NOVOSIBIRSK KATHARINA DORT, UNIV. OF GIESSEN

WHAT’S THE STATUS? � 14 PHIPSI19 NOVOSIBIRSK KATHARINA DORT, UNIV. OF GIESSEN

STATUS - MONOPOLE SIMULATION Testbeam at DESY and CERN Minimum ionizing particles DEPFET Technology, Test Beam Performance at Taller de Altas Energías 2013 by Boronat et al. � 15 PHIPSI19 NOVOSIBIRSK KATHARINA DORT, UNIV. OF GIESSEN

STATUS - MONOPOLE SIMULATION •Preliminary simulation of 1 GeV magnetic monopoles with unit charge : Belle II Simulation Belle II Simulation Preliminary Preliminary � 16 PHIPSI19 NOVOSIBIRSK KATHARINA DORT, UNIV. OF GIESSEN

STATUS - MONOPOLE SIMULATION •Preliminary simulation of 1 GeV magnetic monopoles with unit charge : Background Monopoles Belle II Simulation Belle II Simulation Preliminary Preliminary � 17 PHIPSI19 NOVOSIBIRSK KATHARINA DORT, UNIV. OF GIESSEN

STATUS - IDENTIFICATION OF ANTI-DEUTERONS •Branching fraction in decay: Γ i / Γ < 1.3 ⋅ 10 − 5 Υ (4 S ) Belle II Simulation Belle II Simulation Preliminary Preliminary � 18 PHIPSI19 NOVOSIBIRSK KATHARINA DORT, UNIV. OF GIESSEN

STATUS - CLASSIFICATION WITH NEURAL NETWORK Preliminary Preliminary •Motivation: Online •Challenge: Background at identification with PXD to least four orders of prevent loss of HIP events magnitude higher � 19 PHIPSI19 NOVOSIBIRSK KATHARINA DORT, UNIV. OF GIESSEN

OUTLOOK AND CONCLUSION • Challenge: Identification of HIPs complicated due to short range in detector • Strategy: HIP identification with the Belle II Pixel Detector • Status: Feasibility study underway / implementation of monopole simulation currently evaluated • Future Objective : HIP identification on hardware level � 20 PHIPSI19 NOVOSIBIRSK KATHARINA DORT, UNIV. OF GIESSEN

OUTLOOK AND CONCLUSION • Challenge: Identification of HIPs complicated due to short Thank you for your range in detector attention! • Strategy: HIP identification with the Belle II Pixel Detector Спасибо за • Status: Feasibility study underway / implementation of внимание ! monopole simulation currently evaluated • Future Objective : HIP identification on hardware level � 21 PHIPSI19 NOVOSIBIRSK KATHARINA DORT, UNIV. OF GIESSEN

BACK-UP � 22 PHIPSI19 NOVOSIBIRSK KATHARINA DORT, UNIV. OF GIESSEN

SUPER-KEKB First collision: April 2018 0.5 fb − 1 Phase II: ~ � 23 PHIPSI19 NOVOSIBIRSK KATHARINA DORT, UNIV. OF GIESSEN

MONOPOLE PRODUCTION • Monopole pair production: e + e − → γ * → M + M − • No perturbative treatment possible due α m ≈ 34 n 2 to large coupling constant •Based on QED pair production: σ ( e + e − → M + M − )/ σ ( e + e − → μ + μ − ) ∝ β 3 ( ng e ) 2 � 24 PHIPSI19 NOVOSIBIRSK KATHARINA DORT, UNIV. OF GIESSEN

WHY NOT DETECTED YET? • General-purpose detectors in Characterize detector with HIP today’s particle physics source (e.g. alpha emitter) experiments not suitable for HIPs •Short range prevents activation of Provide (partial) particle identification with inner detectors trigger •Conventional tracking algorithms Implement Monopole-tracking do not recognize trajectory � 25 PHIPSI19 NOVOSIBIRSK KATHARINA DORT, UNIV. OF GIESSEN

MAGNETIC MONOPOLES • Modified Maxwell equations: ∇ D = 4 πρ e ∇ B = 4 πρ m −∇ × E = 1 ∂ t B + 4 π ∂ c j m c ∇ × H = 1 ∂ t D + 4 π ∂ c j e . c � 26 PHIPSI19 NOVOSIBIRSK KATHARINA DORT, UNIV. OF GIESSEN

STATUS - MONOPOLE SIMULATION •Preliminary simulation of 1 GeV magnetic monopoles with unit charge : Belle II Simulation Belle II Simulation Preliminary Preliminary � 27 PHIPSI19 NOVOSIBIRSK KATHARINA DORT, UNIV. OF GIESSEN

NEURAL NETWORKS � 28 PHIPSI19 NOVOSIBIRSK KATHARINA DORT, UNIV. OF GIESSEN