Antiproton-proton elastic scattering as a day-1 experiment at HESR March 14-18, 2011 Darmstadt Antiproton-proton elastic scattering as a day-1 experiment at HESR Huagen Xu LuMo @ IKP: J. Ritman, T. Stockmanns and T. Randriamalala 2018/5/19 1 1

Outline Introduction to PANDA luminosity monitor Proposal of the day-1 experiment Design of the day- 1 experiment Summary and outlook 2018/5/19 2 2

1. Panda luminosity monitor Goal of Panda luminosity monitor: Integrated luminosity with ~ 3% absolute precision PANDA facility Concept: Low t elastic scattering, Coulomb interference region Forward going antiproton, 3 <Θ< 8 mrad 4-layer Si-strip telescope at z~10m 50 um pitch, double sided 2018/5/19

The measurable t is limited to a small range! Performance evaluation with pure elastic events PANDA Setting for event generator(DPM): Plab : 6.2 GeV/c, pure elastic events Theta_min : 0.113°(~1.98mrad) Events : 5M Parameters : σel = 18.97mb, σtot = 64.50mb, b = 11.89(GeV/c)-2, ρ = - 0.063 t: [0.0002-0.03] lumi: ~ 0.39% The measurable t is limited to a small range! 2018/5/19 4 4

Fixing the parameters is needed to determine the absolute luminosity! Parameters correlation Only Lumi free ~0.34% Both rho & Lumi free ~2.29% ρ sensitive region Fixing the parameters is needed to determine the absolute luminosity! 2018/5/19 5 5

Luminosity uncertainty Luminosity calibration error 2. Proposal of day-1 experiment Few data existing in PDG for σtot and ρ within PANDA momentum region! Motivation 1: To determine the parameters for Panda absolute luminosity calibration Motivation 2: Physics itself (to obtain accurate values for the unknown parameters σtot , ρ and b) Experiment strategy: luminosity-independent measurement Luminosity uncertainty Parameters error Luminosity calibration error Error loop should be avoided! 2018/5/19 6 6

Parameters determination Typical parameterization σtot and ρ b dominant region Optical point Optical theorem Parameterization for slope b for |t| < 0.8 GeV2 , moderate energies (5-30GeV) Luminosity independent analysis is feasible! 2018/5/19 7

Large t-range measurement at HESR Proposed location Large t-range: 0.0008-0.1 GeV2 in order to reduce the parameters effect less than 1% on luminosity determination Enough space in the early phase running of HESR Antiproton-proton elastic scattering with coincidence at HESR! 2018/5/19 8 8

3. Design of day-1 experiment Sketch of general design Z θ’ target X Y α = π/2 - θ’ Forward measurement Recoils measurement beam Kinetic correlation Background suppression 2018/5/19 9 9

Recoil arm Requirements for design: Recoil angle for t:[0.0008 – 0.1] GeV2 (~0.4-55MeV) 1.6°-- 17.8°for 1.5 GeV/c 0.9°-- 10.5°for 15.0 GeV/c Windowless cluster jet target To measure recoil protons energy and position Movable detector plane Active 8 cm Overlapping 1 cm 1 4 2 3 Beam axis 5cm 24cm Single sided strip detectors No. 1 and 2 Si strip sensor: 1000μm with 1.2 mm pitch No. 3 and 4 Ge strip sensors: 4mm &10mm with 1.2mm pitch 2018/5/19

Commissioning at COSY in the next couple of years! Status of recoil arm Sensor design is fixed and production will get started by formal order; Front end electronics solution (conventional commercial FEE modules available); Mechanical design of vacuum chamber (in consideration) Cluster jet target (under construction) Building up a test system for detector test, electronics investigation, calibration study and so on (ongoing); Commissioning at COSY in the next couple of years! 2018/5/19 11 11

4. Summary and Outlook Dedicated antiproton-proton elastic scattering as a day- 1 experiment at HESR has been proposed; Design of recoil arm is nearly finished; The forward arm design will be optimized after commissioning of recoil arm at COSY. The complete day-1 experiment needs to be performed in the early running phase of HESR. 2018/5/19 12 12

Thanks for your attention! 2018/5/19 13 13

In PDG database: few data of σtot and ρ; no data of b; Dependence of the uncertainty of absolute luminosity on errors of σtot , ρ and b Err_Lumi vs Err_ σtot Err_Lumi vs ρ Err_Lumi vs Err_b In PDG database: few data of σtot and ρ; no data of b; The existing data are not sufficient for PANDA absolute luminosity calibration! 2018/5/19

Uncertainty of luminosity contributed by σtot PANDA Sigtot (mb) PbarP, 6.2GeV/c Data of σtot in PDG database 2018/5/19 29.06.10 15 15

Uncertainty of luminosity contributed by ρ PANDA PbarP, 6.2GeV/c Data of ρ in PDG database 2018/5/19 16 16

Requirement 1: expected t-range t:Optical point and b Nuclear dominated region t:ρ and σtot Coulomb-strong region Known b,ρ and σtot absolute luminosity <1% b and dNel/dt|t=0 t: [0.05-0.1] GeV2 ρ and σtot t: [0.001-0.02] GeV2 Luminosity error < 1% by parameters 2018/5/19 17 17

Expected t range : 0.0008 – 0.1 (GeV/c)2 2018/5/19 18 18

FEE strategy for strip sensors ASIC-based preamplifier PCB board-based preamplifier modules Both self-trigger capable 2018/5/19

Recoil arm Recoil angle for t: 0.0008 – 0.1 GeV2 (~0.4-55MeV) Motor driver system 18.9° 11° Cooling plate Cooling interface Pump Source mechanism Flange 1, 2 Valve Beam pipe Y 68cm 120cm Beam height 1.4m Recoil angle for t: 0.0008 – 0.1 GeV2 (~0.4-55MeV) 1.6°-- 17.8°for 1.5 GeV/c 0.9°-- 10.5°for 15.0 GeV/c Windowless cluster jet target Using strip detector to measure recoil protons energy and position Movable detector plane Source mechanism for calibration Separate vacuum chamber 2018/5/19

Ratio ρ Typical method ρ sensitive region Optical theorem PLB 385, 1996, 479 (E760) NPB 262, 1985, 689 Typical method ρ sensitive region Optical theorem PLB 537, 2002, 41-44 (E811) 2018/5/19 21 21

Slope b Measurements for slope b Measure dσ/dt on a large t range Away from the Coulomb interference region Traditional parameterization PR D24,1981,26 PR D50,1994,5518 b sensitive region |t|<0.8(GeV/c)2, moderate energies(5-30GeV) 0.05<|t|<1.0(GeV/c)2, beam energies (50-175GeV) (good representation for Fermilab data) Data from SLAC, CERN ISR show even more complicated t dependence 2018/5/19 22 22

Parameters correlation coefficient R(rho,L) = -0.9988 R(sigtot,L) = -1 R(b,L) = 0.9309 2018/5/19