JLEIC Collaboration meeting Spring 2016 Ion Polarization with Figure-8 March 29-31, 2016, Thomas Jefferson National Accelerator Facility Newport News, Virginia USA Ion Polarization with Figure-8 A.M. Kondratenko 1, Ya.S. Derbenev 2, Yu.N. Filatov 3, M.A. Kondratenko 1, F. Lin 2, V.S. Morozov 2 and Y. Zhang 2 1 Science and Technique Laboratory Zaryad, Novosibirsk, Russia 2 Jefferson Lab, Newport News, VA 3Moscow Institute of Physics and Technology, Dolgoprydny, Russia
Outline Features of ion polarization control in figure-8 rings Ion polarization stability in figure-8 rings. Coherent and incoherent parts of the zero-integer spin resonance strength Verification of analytic predictions by spin tracking Analysis of ion polarization stability in the JLEIC collider up to 200 GeV Summary Future plans A. Kondratenko et al, Ion Polarization with Figure-8. JLEIC Collaboration Meeting Spring 2016, March 29-31, 2016, Newport News, Virginia, USA
Spin Motion in Figure-8 Rings Spin transparency in a figure-8 structure Spin precessions in the two arcs are exactly cancelled In an ideal structure (without perturbations) all solutions are periodic The spin tune is zero independent of energy n = 0 A. Kondratenko et al, Ion Polarization with Figure-8. JLEIC Collaboration Meeting Spring 2016, March 29-31, 2016, Newport News, Virginia, USA
Polarization Preservation during Ion Acceleration To preserve the beam polarization during acceleration, it is sufficient to stabilize the spin motion in the zero-integer spin resonance region using one weak solenoid The required solenoid field integral does not exceed 1 Tm at the top energy of the booster. A. Kondratenko et al, Ion Polarization with Figure-8. JLEIC Collaboration Meeting Spring 2016, March 29-31, 2016, Newport News, Virginia, USA
Control of Ion Polarization in Collider Ring 3D spin rotator allows one to adjust any polarization orientation at the interaction point Polarization stability condition The spin tune induced by the PC solenoids must significantly exceed the strength of the zero-integer spin resonance A. Kondratenko et al, Ion Polarization with Figure-8. JLEIC Collaboration Meeting Spring 2016, March 29-31, 2016, Newport News, Virginia, USA
Strength of Zero-Integer Spin Resonance The resonance strength is determined by the average spin perturbation component and consists of coherent and incoherent parts. caused by closed orbit distortions caused by emittances of the synchrotron and betatron oscillations lies in the ring plane is vertical A. Kondratenko et al, Ion Polarization with Figure-8. JLEIC Collaboration Meeting Spring 2016, March 29-31, 2016, Newport News, Virginia, USA
Figure-8 Booster Original 3 GeV/c booster scaled to 8 GeV/c Stabilizing solenoid with B||l < 0.35 Tm A. Kondratenko et al, Ion Polarization with Figure-8. JLEIC Collaboration Meeting Spring 2016, March 29-31, 2016, Newport News, Virginia, USA
Incoherent Part of Resonance Strength in Figure-8 Booster Ideal figure-8 booster, on-momentum particles with 1 cm offsets in x and y Stable polarization direction vertical as expected! Incoherent part of the resonance strength 10-5 -10-4 protons vertical (Zgoubi) (Zgoubi) longitudinal A. Kondratenko et al, Ion Polarization with Figure-8. JLEIC Collaboration Meeting Spring 2016, March 29-31, 2016, Newport News, Virginia, USA
Coherent Part of Resonance Strength in Figure-8 Booster Stable spin direction due to coherent part lies in the horizontal plane RMS closed orbit distortion of a few hundred m On-momentum particle launched along CO Precession rate gives the value of the coherent part of the spin resonance strength protons vertical (Zgoubi) A. Kondratenko et al, Ion Polarization with Figure-8. JLEIC Collaboration Meeting Spring 2016, March 29-31, 2016, Newport News, Virginia, USA
Stabilization of Proton Spin in Figure-8 Booster Figure-8 booster with transverse quadrupole misalignments 0.35 Tm (maximum) spin stabilizing solenoid (=510-3) On-momentum particle with 1 cm offsets in x and y protons (Zgoubi) A. Kondratenko et al, Ion Polarization with Figure-8. JLEIC Collaboration Meeting Spring 2016, March 29-31, 2016, Newport News, Virginia, USA
Incoherent Part of Resonance Strength in Figure-8 Booster Ideal figure-8 booster, on-momentum particles with 1 cm offsets in x and y Stable polarization direction vertical as expected! Incoherent part of the resonance strength <10-8 deuterons vertical (Zgoubi) (Zgoubi) longitudinal A. Kondratenko et al, Ion Polarization with Figure-8. JLEIC Collaboration Meeting Spring 2016, March 29-31, 2016, Newport News, Virginia, USA
Coherent Part of Resonance Strength in Figure-8 Booster Same transverse quadrupole misalignments as for protons On-momentum particle launched along CO, coherent strength part <10-6 0.35 Tm solenoid (=1.510-3), p/p=0 particle with 1 cm offsets in x and y deuterons vertical (Zgoubi) longitudinal (Zgoubi) A. Kondratenko et al, Ion Polarization with Figure-8. JLEIC Collaboration Meeting Spring 2016, March 29-31, 2016, Newport News, Virginia, USA
Coherent Part of Resonance Strength in the JLEIC Collider Assuming RMS closed orbit distortion of ~200 m 2T4m control solenoids allow setting proton and deuteron spin tunes to p=10-2 and d=10-4. This is sufficient for stabilization and control of polarization in the JLEIC collider up to 60 GeV without compensation and up to 100 GeV with compensation. Going above 100 GeV requires additional measures. A. Kondratenko et al, Ion Polarization with Figure-8. JLEIC Collaboration Meeting Spring 2016, March 29-31, 2016, Newport News, Virginia, USA
Compensation of Coherent Part of Resonance Strength up to 100 GeV The first 3D rotator located in the straight containing the interaction point directly controls the polarization. The second 3D rotator with constant solenoid fields is located in the other straight and is used to compensate the coherent part of the zero-integer spin resonance strength. A. Kondratenko et al, Ion Polarization with Figure-8. JLEIC Collaboration Meeting Spring 2016, March 29-31, 2016, Newport News, Virginia, USA
Incoherent Part of Resonance Strength vs Momentum in JLEIC Assuming normalized vertical beam emittance of 0.07 m rad A. Kondratenko et al, Ion Polarization with Figure-8. JLEIC Collaboration Meeting Spring 2016, March 29-31, 2016, Newport News, Virginia, USA
Summary For stability of ion polarization, the spin tune induced by the 3D spin rotator must significantly exceed the strength of the zero-integer spin resonance. Calculations of resonance strength for JLEIC show that its coherent part related to closed orbit distortion is a few orders of magnitude greater than its incoherent part related to beam emittances. 3D rotators with 2 T solenoids provide control of proton and deuteron polarizations in the JLEIC collider up to 100 GeV. Analysis of ion polarization stability in the JLEIC collider up to 200 GeV indicates that one has to take additional measures to preserve and control the polarization, e.g. better orbit control, stronger spin control solenoids, and/or small transverse spin control fields. A. Kondratenko et al, Ion Polarization with Figure-8. JLEIC Collaboration Meeting Spring 2016, March 29-31, 2016, Newport News, Virginia, USA
What is next? Future Plans Spin tracking simulations using verified existing codes Optics optimization and development of ion polarization scheme for up to 200 GeV/c Evaluation and compensation of the spin effect of the detector solenoid Study of non-linear spin effects Evaluation of beam-beam effect on ion polarization and optimization of the response function at the IP Development of ion polarization measurement scheme and spin- flipping system for high precision experiments at the JLEIC collider A. Kondratenko et al, Ion Polarization with Figure-8. JLEIC Collaboration Meeting Spring 2016, March 29-31, 2016, Newport News, Virginia, USA