Polarization of a stored beam by spin filtering

Mitglied der Helmholtz-Gemeinschaft Polarization of a stored beam by spin filtering Christian Weidemann 03. June 2013

Motivation The PAX collaboration proposed to investigate so called Drell-Yan processes in scattering of polarized proton (p) and antiproton (pbar) beams at the HESR (FAIR) Annihilation of valence quark with an antivalence quark allows access to a multitude of findings: transversity,. antiproton proton Requirements: Polarized proton beam Polarized antiproton beam

How to Polarize Antiprotons? Spin-1/2 particles 2 states selective removal selective flip unpolarized polarized unpolarized polarized Selective removal reduces beam intensity Selective flip leaves intensity + e p spin-flip cross-section is too low to use selective flip σ < 3.2 * 10 7 b σ < 1.7 * 10 7 b D. Oellers. et al., Phys. Lett. B 674 (2009) 269

Spin filtering tot How to Polarize Antiprotons? Polarization build-up of a circulating particle beam by interaction with a polarized gas target 0 1( PQ) 2( Pkˆ)( Qkˆ) P beam particle spin orientation Q target particle spin orientation k beam direction N N t P( t) tanh t Q d N N ~ 1 1 t f unpolarized p beam polarized target

Spin filtering tot How to Polarize Antiprotons? Polarization build-up of a circulating particle beam by interaction with a polarized gas target 0 1( PQ) 2( Pkˆ)( Qkˆ) P beam particle spin orientation Q target particle spin orientation k beam direction N N t P( t) tanh t Q d N N ~ 1 1 t f polarized p beam polarized target

Spin filtering tot How to Polarize Antiprotons? Polarization build-up of a circulating particle beam by interaction with a polarized gas target 0 1( PQ) 2( Pkˆ)( Qkˆ) P beam particle spin orientation Q target particle spin orientation k beam direction N N t P( t) tanh t Q d N N ~ 1 1 t f polarized p beam polarized target

Spin Filtering at COSY Spin filtering with protons for better understanding of the underlying processes and commissioning of the experimental setup Length: 183.4 m Injection energy: 45 MeV Electron cooling for long lifetimes up to 600 MeV/c (p) Spin Flipper COSY

Spin Filtering at COSY N N t P( t) tanh ~ 1 N N 1 f Q d t t 1. Maximum polarizing cross section small kinetic energy, where the analyzing power is known COSY measurement possible energy range FILTEX F. Rathmann. et al., PRL 71, 1379 (1993) FILTEX at T=49.3 MeV Ay is known

Spin Filtering at COSY N N t P( t) tanh ~ 1 N N 1 f Q d t t 1. Maximum polarizing cross section small kinetic energy 2. Maximum revolution frequency large kinetic energy (compromise between 1. & 2. needed) short accelerator (we use COSY)

Spin Filtering at COSY N N t P( t) tanh ~ 1 N N 1 f Q d t t 1. Maximum polarizing cross section small kinetic energy 2. Maximum revolution frequency large kinetic energy short accelerator 3. Maximum target polarization and density high dense polarized gas target (Atomic Beam Source) storage cell

Spin Filtering at COSY N N t P( t) tanh ~ 1 N N 1 f Q d t t 1. Maximum polarizing cross section small kinetic energy 2. Maximum revolution frequency large kinetic energy short accelerator 3. Maximum target polarization and density high dense polarized gas target (Atomic Beam Source) storage cell 4. Maximum filtering time long beam lifetime (UHV, good beam preparation, etc.)

Spin-filter Equipment at PAX-IP ABS Low-β Quadrupoles BRP Target Chamber

Spin-filter Equipment at PAX-IP Beam lifetime: d t 1 Low-β section off Low-β section on

Spin-filter Equipment at PAX-IP PAX vacuum section IG pumps 100 l/s NEG coated beam pipes (each 5000 l/s) IG pumps 100 l/s

Spin-filter Equipment at PAX-IP PAX target chamber Fast shutters (<15 ms) Flow limiters (d = 19 mm, l = 80 mm) SAES getter pump (each 1900 l/s) HiPace 1800 turbo (1200 l/s)

Spin-filter Cycle Unpolarized proton beam injected with Tp = 45 MeV Accelerate to Tp = 49. 3 MeV + beam preparation Start filtering (0s) with switching on ABS target Stop filtering (12000s) (ABS off) Start beam polarization measurement (Cluster target on + Spin flipper) Switch holding field polarity for the next cycle

Beam Polarization Measurement Measurement of asymmetry in pd-elastic scattering 2 Silicon Tracking Telescops left and right of the COSY beam Deuterium Cluster Target ( d 10 14 atoms/cm 2 ) t

Beam Polarization Measurement Measurement of asymmetry in pd-elastic scattering 2 Silicon Tracking Telescops left and right of the COSY beam Deuterium Cluster Target ( d 10 14 atoms/cm 2 ) t Top view Detectors measure E, Θ, φ Particle identification Selection of elastic scattering events cluster target

P [GeV/c] P [GeV/c] de (STT1_1) [MeV] de (STT1_2) [MeV] Beam Polarization Measurement Energy loss in 1. vs 2. layer de Energy (STT1_2) lossvs in de 2. vs (STT1_3) 3. layer deuterons deuterons protons protons Deuteron momentum vs. scattering angle de (STT1_2) [MeV] Proton momentum vs. scattering angle de (STT1_3) [MeV] Θ [deg] Θ [deg]

Beam Polarization Measurement L Events in left and right detector, R, t = 0s t = 12000s

Results P measured for 0s, 12000s and 16000s filtering time Polarization build with time: dp dt (4.8 0.8) 10 7 s 1 Polarizing cross section: W. Augustyniak. et al., Phys. Lett. B 718 (2012) 64 Theory:

Summary Achievements: Beam development procedure to provide beam lifetimes of about 10000 s Installation and operation of experimental equipment in COSY (Low-β section, polarized target, vacuum system, etc. ) Successful spin-filtering experiment in 2011 Confirmation of the theoretical predictions

Summary Achievements: Beam development procedure to provide beam lifetimes of about 10000 s Installation and operation of experimental equipment in COSY (Low-β section, polarized target, vacuum system, etc. ) Successful spin-filtering experiment in 2011 Confirmation of the theoretical predictions Future activities: Spin filtering with protons and a longitudinally polarized gas target at COSY at Tp = 130 MeV ( p p scattering) Spin-filtering experiments at AD exploring the systems p(bar)p, p(bar)d, 3 (p(bar) He) (transverse and longitudinal polarization) Spin observables in pd breakup reactions between 30 and 50 MeV proton beam energy Time Reversal Invariance Test at COSY at Tp = 150 MeV ( scattering) New Polarimeter will be build pd

Summary Achievements: Beam development procedure to provide beam lifetimes of about 10000 s Installation and operation of experimental equipment in COSY (Low-β section, polarized target, vacuum system, etc. ) Successful spin-filtering experiment in 2011 Confirmation of the theoretical predictions Future activities: Spin filtering with protons and a longitudinally polarized gas target at COSY at Tp = 130 MeV ( p p scattering) Spin-filtering experiments at AD exploring the systems p(bar)p, p(bar)d, 3 (p(bar) He) (transverse and longitudinal polarization) Spin observables in pd breakup reactions between 30 and 50 MeV proton beam energy Time Reversal Invariance Test at COSY at Tp = 150 MeV ( scattering) New Polarimeter will be build pd

Additional Slides

Beam Polarization Measurement

Systematics Spin-flip efficiency 99 flips

Polarization lifetime Systematics Deuteronen Protonen 5000s

Kinematics

beam current H0 (cooling) revolution frequency

Spin-filter Cycle trigger rate beam current pressure at filter target pressure at cluster target p [mbar]

Figure of Merit

Cross Section

Spin-filter Equipment at PAX-IP

How to Polarize Antiprotons? + e p spin-flip cross-section is too low 3 2 1 1 2 σ < 3.2 * 10 7 b σ < 1.7 * 10 7 b Slide 35

Spin-filter Equipment at PAX-IP Atomic Beam Source

Spin-filter Equipment at PAX-IP PAX target chamber SAES getter pump (each 1900 l/s) HiPace 1800 turbo (1200 l/s)

Silicon Tracking Telescope cooled vacuum electronics cooling feedthrough front-end electronics detectors

Siberian Snake Superconducting 4.7 Tm solenoid is ordered Length 1m Ramping time: 30 s

New Polarimeter Simulations Result

New Polarimeter Design

New Polarimeter Detectors Detector Coupling HERMES TIGRE 300 μm AC Thickness (μm) 300 Activearea (mm) No. ofstrips 128 Strip pitch (μm) 758 Depl. voltage (V) 8 modules available Suitable for 1 st and 2 nd layer of detection system 50 μm polyimide with 5 μm copper traces Existing Helix front-end has to be removed Connect new pitch adapter to VA32TA2 Bonding to Kapton

New Polarimeter Cooling System (Design and Tests)) Cooling and temperature stabilization of detectors and electronics is needed Survive 450 C NEG activation and 80 C target chamber bake-out Conductive cooling will be utilized Simulations are under way Prototype design and tests are in progress Test-bench with diagnostic system is prepared (thermocamera and temperature sensors)

QCD Partonenmodell well known momentum distribution valence quark known helicity distribution gluon sea quarks unknown transversity distribution spin of the proton spin of the quark

Diagonal Scaling Yield i Y 00 Y 10 Y 20 Y 30 Y 01 Y 11 Y 21 Y 31 Y 02 Y 12 Y 22 Y 32 Y 03 Y 13 Y 23 Y 33 Combinations of beam and target polarization 4 quadrants (detectors) reduced matrix sum of rows: sum of columns: X E i ii Y r i x ik k c k x ik i kk Dn k Extraction of all flipping and non flipping components possible Luminosities Detector Efficiencies

Expected Polarizations for p(bar) transversal longitudinal A D

Spin Filtering with Longitudinal Polarization (COSY)

Time Reversal Invariance Test

Time Reversal Invariance Test How to measure the total cross section? Transmission experiment! Optical theorem: Beam current transformer at COSY Y. Valdau, COSY proposal #215

Study of three nucleon continuum in proton deuteron breakup reactions between 30 an 50 MeV proton beam energy Test the predictive power of chiral EFT: Most general Lagrangian formulated based on the symmetry of low-energy-qcd Using the PAX facility Detector: Measurement of vector and tensor analyzing powers and spin correlation coefficients - 3rd layer of 1.5 mm thickness is required P.Thörngren, COSY proposal #202.1

Target Holding Field System The target holding field system provides magnetic guide fields in the order of 1 mt in x-, y-, and z-direction Switching of polarization within 10 ms Compensation coils avoid influences on the beam axis

Target Holding Field System x-direction y-direction z-direction