Resonance depolarization method Ivan Nikolaev BINP-IHEP seminar Budker Insitute of Nuclear Physics Novosibirsk, Russia December 17, 2019 Ivan Nikolaev (BINP , Novosibirsk, Russia) Resonance depolarization method December 17, 2019 1 / 26
Outline 1 Introduction 2 The idea of the method 3 Radiative polarization 4 Polarization measurement Touschek polarimeter at VEPP-4M Laser polarimeter at VEPP-4M 5 Summary Ivan Nikolaev (BINP , Novosibirsk, Russia) Resonance depolarization method December 17, 2019 2 / 26
Introduction Precision measurement of the mass of the elementary particles in colliding experiments requires precise beam energy calibration Resonace depolarization technique The most precise method of beam energy measurement ∆ E / E ∼ 10 − 6 Suggested and firstly applied in BINP (Novosibirsk) at 1971 Baier, Sov. Phys. Usp. 14 695–714 (1972) Used in experiments of precise mass measurement in the wide energy range Skrinskii, Shatunov, Sov. Phys. Usp. 32 548–554 (1989) Energy calibration for some synchrotron light sources: ESSY-I, BESSY-II,ALS,SLS, ANKA, SOLEIL Ivan Nikolaev (BINP , Novosibirsk, Russia) Resonance depolarization method December 17, 2019 3 / 26
Used in experiments of precise mass maeasurement Particle Experiment Date Φ , K ± VEPP-2M OLYA 1975-1979 J /ψ , ψ ( 2 S ) VEPP-4 OLYA 1980 Υ( 1 S ) , Υ( 2 S ) , Υ( 3 S ) VEPP-4 MD-1 1982-1986 Υ( 1 S ) CESR CUSB 1984 Υ( 2 S ) DORIS II ARGUS, Crystal Ball 1983 K 0 , ω VEPP-2M CMD 1987 Z LEP ALEPH, DELPHI, L3, OPAL 1993 J /ψ , ψ ( 2 S ) , τ , D 0 , D ± ψ ( 3770 ) VEPP-4M KEDR 2003-2015 Ivan Nikolaev (BINP , Novosibirsk, Russia) Resonance depolarization method December 17, 2019 4 / 26
The idea of the method TEM-wave depolarizer Spin precession Frenkel,Thomas (1926), v Bargmann, Michel, Telegdi (1959) e - ds i S d τ = 2 µ F ij s j − 2 µ ′ u i F jk u j s k B 1 + γ µ ′ � � dynamic kinematic (Thomas) precession Ω = ω 0 = ω 0 n ± ω d , n ∈ Z � ����������������� �� ����������������� � µ 0 � ����� �� ����� � v × ˙ s × � B ′ d � 2 µ� ( γ − 1 ) � s × [ � � v ] s = � Ω × � dt = + s δ ( µ ′ /µ 0 ) ≈ 2 . 3 × 10 − 10 δ m e ≈ 2 . 2 × 10 − 8 γ v 2 � � n − 1 ± ω d E = ( 440 . 6484431 ± 0 . 0000097 ) [MeV] × ω 0 Ivan Nikolaev (BINP , Novosibirsk, Russia) Resonance depolarization method December 17, 2019 5 / 26
Energy calibration accuracy Measurement of the spin precession frequency by resonance depolarization ( ∼ 1 keV ) 1 Calculation of average beam energy ( ∼ 2 keV ) 2 Calculation of average beam energy at the interaction point ( ∼ 1 keV ) 3 Calculation of luminosity wighted average c.m. energy ( ∼ 1 keV ) 4 More about corrections and errors to center of mass energy Bogomyagkov, et al., RUPAC-2006-MOAP02. Nikitin, RUPAC-2006-MOAP01. Bogomyagkov, et al., Conf. Proc. C 070625 (2007) 63. Ivan Nikolaev (BINP , Novosibirsk, Russia) Resonance depolarization method December 17, 2019 6 / 26
Radiative polarization Radiative polarization at VEPP-2M observed Sokolov-Ternov effect (1963) with Touschek polarimeter, τ = 70 min (1974) Serednyakov, Skrinskii, Tumaikin, Shatunov, JETP , V44, No. 6, p.1063 (1976) Sokolov, Ternov, Dokl.Akad.Nauk SSSR 153 (1963) no.5, 1052-1054 Intensity of SR with spin flip � ω c � 2 4 W ↑↓ ≈ W 0 3 E √ � H 0 � 3 1 P 0 = 8 3 Ż C τ p = P 0 ≈ 92 . 4 % α c γ 2 H 15 First observation VEPP-2 (Novosibirsk) in 1970 Baier, Sov. Phys. Usp. 14 695–714 (1972) ACO storage ring (Orsay) in 1972 P ( t ) = P τ � 1 − e − t /τ � τ d τ p ; τ = Duff, Marin, Masnou, Sommer, Preprint, Orsay 4-73(1973) τ p τ p + τ d Ivan Nikolaev (BINP , Novosibirsk, Russia) Resonance depolarization method December 17, 2019 7 / 26
Depolarizing resonances ν = Ω − 1 = k · ν x + l · ν y + m · ν s + n k , l , m , n ∈ Z ω 0 Stochastic depolarization � � − 1 | w k | 2 � ν 2 τ d ∼ 0 ( ν 0 − ν k ) 4 Difficult to accelerate polarized beam due to resonance cross Spin precession shift � | w k | 2 δν ∼ 1 Equilibrium polarization degree measurement at VEPP-4 2 ν 0 − ν k with laser polarimeter. Ivan Nikolaev (BINP , Novosibirsk, Russia) Resonance depolarization method December 17, 2019 8 / 26
Obtaining polarization at VEPP-4M Polarization time Ring VEPP-3 VEPP-4M 12 1540 τ p [h] E [ GeV ] 5 E [ GeV ] 5 τ p @ 1.55 GeV 1.34 h 172 h τ p @ 1.85 GeV 0.56 h 71 h τ p @ 4.1 GeV 80 min τ p @ 4.73 GeV 39 min Good beam polarization for J /ψ , ψ ( 2 S ) , Υ( 1 S ) , Υ( 3 S ) Problem with τ lepton energy region (close to integer ν = 4 resonance) Ivan Nikolaev (BINP , Novosibirsk, Russia) Resonance depolarization method December 17, 2019 9 / 26
Polarization measurement Fixed target Mott scattering (spin orbit coupling, 100 kev < E < 5 MeV): JLab Moller scattrinc (atomic electron, � 1 GeV): JLab, BINP , . . . Touschek (intrabeam scattering) polarimeter (BINP , BESSY-I/II, ALS, SLS. . . ). Best for lower energies E < 2 GeV Compton backscattering (better for high energies E > 5 GeV ) laser: Cornell (CESR), DESY (DORIS), BINP (VEPP-4), SLAC (SLD) . . . synchrotron light from clashing (positron) beam: BINP (VEPP-2M, VEPP-4) Synchrotron spin-light: BINP (VEPP-4) . . . Ivan Nikolaev (BINP , Novosibirsk, Russia) Resonance depolarization method December 17, 2019 10 / 26
Touschek polarimeter Itra-beam scattering ( e − e − → e − e − ) scattering Proposal to use beam lifetime to detect sin 2 θ � � polarization in 1968 (flat beam calculation) 1 − ( � s 1 � d σ = d σ 0 s 2 ) Baier, Khoze, Atomnaya ´ 1 + 3 cos 2 θ Energiya, V25, No.5, pp. 440–442 (1968) Tumaikin’s proposal to use scint. counters N 2 dN (1970) V γ 2 (∆ p / p ) 2 ( 1 − P 2 η ) dt ≈ A Calculation for 2D beam Serednyakov, Skrinskii, Tumaikin, Shatunov, JETP , V44, No. 6, p.1063 (1976) Touschek counters With some relativistic corrections (1978) Baier, Katkov, Strakhovenko, Dokl.Akad.Nauk SSSR, 1978, V241,No4, e - e - P .797–800 v e - with Coulomb effects (1978) S Baier, Katkov, Strakhovenko, Dokl.Akad.Nauk SSSR, 1978, V241,No4, P .797–800 B Ivan Nikolaev (BINP , Novosibirsk, Russia) Resonance depolarization method December 17, 2019 11 / 26
Touschek polarimeter at VEPP-4M depolarizer plates depolarizer plate scintillator 2 4 positron electron beam beam 3 polarized 1 electron beam м м 5 min 8 . 5 R 4 R (E=1.85 GeV) ITP bellows light guide scintillator VEPP-4M cups RF signal input LINAC counters VEPP-3 7 5 KEDR 6 8 8 movable scintillator counters located inside vacuum chamber at different places of VEPP-4M Ivan Nikolaev (BINP , Novosibirsk, Russia) Resonance depolarization method December 17, 2019 12 / 26
Touschek polarimeter at VEPP-4M System performance Energy range 1 . 5 ÷ 2 . 0 GeV > 0 . 1 mA Beam current Number of bunches (electron or positron) 4 1 MHz (50 kHz/mA 2 / counter ) Count rate ∆ = ˙ N pol / ˙ Compensation technique N unpol − 1 ∆ = 1 ÷ 3 % Depolarization effect Polarization degree ≈ 80 % 1 keV (10 − 6 ) Stat accuracy Number of calibration at same bunches 3 Calibration duration 2 hours Number of energy calibrations since 2001 ≈ 4000 Ivan Nikolaev (BINP , Novosibirsk, Russia) Resonance depolarization method December 17, 2019 13 / 26
Energy calibration example 2008-10-18-02:36:02 Run 3136 χ χ 2 2 / ndf / ndf 59.14 / 30 59.14 / 30 0.02 371.4 371.4 0.4485 0.4485 T T ± ± DELTA DELTA 0.01371 0.01371 0.0002082 0.0002082 ± ± CONST CONST 0.005489 0.005489 0.0001431 0.0001431 ± ± SLOPE1 SLOPE1 5.965e-06 5.965e-06 ± ± 6.456e-07 6.456e-07 SLOPE2 SLOPE2 3.162e-06 3.162e-06 7.994e-07 7.994e-07 ± ± 0.01 1851.744 1851.738 1851.732 1851.726 1851.720 1851.714 1851.708 1851.702 1851.696 1851.690 1851.684 1851.678 1851.672 1851.666 1851.660 1851.654 1851.648 1851.642 1851.636 1851.630 1851.624 1851.619 1851.613 1851.607 1851.601 1851.595 1851.589 1851.583 1851.577 0 0 200 400 600 800 Ivan Nikolaev (BINP , Novosibirsk, Russia) Resonance depolarization method December 17, 2019 14 / 26
Several calibrations with same polarized bunch 2004-09-16-02:36:55 PSSW Run 1120 1893.24 0.035 М eV E = (1888.2195 0.001) ± 0.05 1 М eV E = (1888.2194 ± 0.001) 2 0.030 0.045 E = 1888.337 0.002 MeV ± 2nd depolarization 3 0.04 E = 1888.338 0.002 MeV 0.025 ± 2 ∆ In = 183.66725 kHz 1st deplarization 0.035 Out = 140.02785 kHz 0.020 E = 1888.343 0.001 MeV ± 1 inf kHz/mA^2 0.03 1888.375458 1888.341021 1888.323802 1888.306584 1888.305906 1888.323124 1888.340343 1888.357562 1888.363895 1888.346676 1888.329458 1888.312239 1888.323399 1888.340618 1888.357836 1888.375055 1888.323399 1888.340618 1888.357836 1888.375055 0.015 1888.35824 1888.37478 1888.29502 1888.30618 1888.30618 0.025 0 200 400 600 800 1000 1200 1400 1600 1800 0 200 400 600 800 1000 1200 1400 1600 1800 time (s) t (s) Fd = (-585234.4319+-2.87)Hz Triple jump Double jump Double up-down scan increase reliability of energy calibration. Suppress cases of calibration at side 50 Hz spin resonances Ivan Nikolaev (BINP , Novosibirsk, Russia) Resonance depolarization method December 17, 2019 15 / 26
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