Perspective in polarized ion sources developments Vadim Dudnikov, Muons, Inc., Batavia, IL USA A Special Beam Physics Symposium in Honor of Yaroslav Derbenev’s 70th Birthday; Aug. 2 & 3, 2010 Muons, Inc. 1

Budker Institute of Nuclear Physics Self-stabilization of e-p instability BNL V.Dudnikov 2 June 2006

G.I. Budker, founder and director of INP

Round table BINP King Arthur Pub Round table of BINP is the method of problems solving

Traditional Siberian folk’s handicrafts in BINP: Electron cooling; Siberian Snakes; Negative ion sources; Neutral Beam Injectors; Superconducting wigglers; Sources of Polarized particles: Industrial accelerators; Storage Rings; Muons colliders……. The electron cooling force in a magnetized electron beam with an anisotropic electron velocity distribution was derived by Derbenev and Skrinsky in 1978 [1]. [1] Ya. S. Derbenev and A. N. Skrinskii, Magnetization effects in electron cooling, Sov. J. Plasma Phys. 4(3), May–June 1978,

HELICAL SIBERIAN SNAKES There are several methods to reduce the depolarizing effect of the resonance field harmonics, but the Siberian snake technique was demonstrated to be most effective in maintaining beam polarization. A snake is a configuration of magnets that, in the orbit frame, rotates the spin by 180 o about an axis which lies in the horizontal plane. This proposal has been made by Y.S.Derbenev and A.N.Kondratenko[1,2]. [1]. Ya.S.Derbenev and A.N.Kondratenko, Proceedings of 10-th International Conference on High Energy Accelerators, Protvino, USSR, [2] Ya.S.Derbenev and A.N.Kondratenko, Proc. Int. Conf. on High Energy Physics with Polarized Beams and Polarized Targets, Argonne, III, (1978), p. 292ff.

Slava in INP. Slides of Siberian Snakes become best awards for VIPs

Workshop on high –energy spin physics, Protvino, IHEP, September,1983 Ya.Derbenev- “Siberian snake”.

Requirements to the polarized source. High intensity ~ 5·10 11 H - /pulse at 200 MeV after the Linac. At booster beam intensity acceptances are limited by about 1·10 11 protons/bunch. The intensity excess can be used to reduce transversal and longitudinal beam emittances by a strong dynamical collimation in the Booster. Highest possible polarization is required to reduce a systematical and statistical errors in polarization experiments. Double spin asymmetry statistical error is proportional to ~ 1/sqrt(L P 4), therefore a 5% polarization increase in the source (or 5% polarization losses decrease in booster and EIC is effectively equivalent to 30% increase in the data taking time. Beam intensity and polarization must be equal at spin-reversal and from pulse to pulse. ΔI/I <10 -3 and ΔP/P < 1% need be reached.

Motivation for high polarization We need particle sources with a highest polarization because polarization can be preserved during acceleration by Siberian Snake and by Figure-8 rings. Ion sources for production of polarized negative and positive light and heavy ions will be considered. Atomic bean ion source can be used for generation of polarized H-, H+, D-, D+, He++, Li +++ ions with high polarization and high brightness. Generation of multicharged ions, injection and beam instabilities will be considered. References: Belov A.S., Dudnikov V.,et. al., NIM A255, 442 (1987). Belov A.S., Dudnikov V.,et al.,. NIM A333, 256 (1993). Belov A.S, Dudnikov V., et. al., RSI, 67, 1293 (1996). Bel’chenko Yu. I., Dudnikov V., et. al., RSI, 61, 378 (1990) Belov A.S. et. al., NIM, A239, 443 (1985). Belov A.S. et. al., 11 th International Conference on Ion Sources, Caen, France, September 12-16, 2005; A.S. Belov, PSTP- 2007, BNL, USA; A.S. Belov, DSPIN2009, DUBNA, Russia; A. Zelenski, PSTP-2007, BNL, USA; DSPIN2009, DUBNA, Russia Muons, Inc. 10

EIC Design Goals  Energy Center-of-mass energy between 20 GeV and 90 GeV energy asymmetry of ~ 10,  3 GeV electron on 30 GeV proton/15 GeV/n ion up to 9 GeV electron on 225 GeV proton/100 GeV/n ion  Luminosity up to cm -2 s -1 per interaction point  Ion Species Polarized H, D, 3 He, possibly Li Up to heavy ion A = 208, all striped  Polarization Longitudinal polarization at the IP for both beams Transverse polarization of ions Spin-flip of both beams All polarizations >70% desirable  Positron Beam desirable Muons, Inc. 11 Yuhong Zhang For the ELIC Study Group Jefferson Lab

ELIC (e/A) Design Parameters IonMax Energy (E i,max ) Luminosity / n (7 GeV x E i,max ) Luminosity / n (3 GeV x E i,max /5) (GeV/nucleon)10 34 cm -2 s cm -2 s -1 Proton Deuteron H He He C Ca Pb * Luminosity is given per unclean per IP

Existing Sources Parameters Universal Atomic Beam Polarized Sources (most promising, less expensive for repeating): IUCF/INR CIPIOS: Pulse Width Up to 0.5 ms (Shutdown 8/02); Peak Intensity H-/D- 2.0 mA/2.2 mA; Max Pz/Pzz 85% to 95%; Emittance (90%) 1.2 π·mm·mrad. INR Moscow: Pulse Width > 0.1 ms (Test Bed since 1984); Peak Intensity H+/H- 11 mA/4 mA; Max Pz 80%/95%; Emittance (90)% 1.0 π·mm·mrad/ 1.8 π·mm·mrad; Unpolarized H-/D- 150/60 mA. OPPIS/BNL: H- only; Pulse Width 0.5 ms (in operation); Peak Intensity >1.6 mA; Max Pz 85% of nominal Emittance (90%) 2.0 π·mm·mrad. Muons, Inc.

First polarized-proton sources described at the INTERNATIONAL SYMPOSIUM ON POLARIZATION PHENOMENA OF NUCLEONS Basel, July 1960 Sources of Polarized Ions a review of early work SOURCES OF POLARIZED IONS BY W. HAEBERLI ANNUAL REVIEW OF NUCLEAR SCIENCE Vol. 17, 1967 The status 40 years ago: W. Haeberli, PSTP-2007, BNL, USA

Method based on 1968 proposal (NIM 62 p. 335)  = 22x cm 2 at 2keV -> 100x cm 2 at 10eV   A.S. Belov et al. (INR-Moscow) - 20 yrs development work Intense beam of unpolarized D - from deuterium surface-plasma ionizes an atomic Beam (2x10 17 H 0  sec puled) Pulsed 4 mA H -  95% Polarization BELOV “ W. Haeberli, PSTP-2007, BNL, USA

A. Belov & V. Derenchuk: ABPIS developers

ABPIS with Resonant Charge Exchange Ionization and Surface-Plasma D- generation Muons, Inc. INR Moscow H 0 ↑+ D+ ⇒ H+↑+ D 0 D 0 ↑+ H+ ⇒ D+↑+ H 0 σ~ cm 2 H 0 ↑+ D− ⇒ H−↑+ D 0 D 0 ↑+ H− ⇒ D−↑+ H 0 σ~ cm 2 A. Belov, DSPIN2009

Atomic Beam Polarized Ion source In the ABS, hydrogen or deuterium atoms are formed by dissociation of molecular gas, typically in a RF discharge. The atomic flux is cooled to a temperature 30K - 80K by passing through a cryogenically cooled nozzle. The atoms escape from the nozzle orifice into a vacuum and are collimated to form a beam. The beam passes through a region with inhomogeneous magnetic field created by sextupole magnets where atoms with electron spin up are focused and atoms with electron spin down are defocused. Nuclear polarization of the beam is increased by inducing transitions between the spin states of the atoms. The transition units are also used for a fast reversal of nuclear spin direction without change of the atomic beam intensity and divergence. Several schemes of sextupole magnets and RF transition units are used in the hydrogen or deuterium ABS. For atomic hydrogen, a typical scheme consists of two sextupole magnets followed by weak field and strong field RF transition units. In this case, the theoretical proton polarization will reach Pz = _1. Switching between these two states is performed by switching between operation of the weak field and the strong field RF transition units. For atomic deuterium, two sextupole magnets and three RF transitions are used in order to get deuterons with vector polarization of Pz = _1 and tensor polarization of Pzz= +1, -2 Different methods for ionizing polarized atoms and their conversion into negative ions were developed in many laboratories. The techniques depended on the type of accelerator where the source is used and the required characteristics of the polarized ion beam (see ref. [2] for a review of current sources). For the pulsed atomic beam-type polarized ion source (ABPIS) the most efficient method was developed at INR, Moscow [3-5]. Polarized hydrogen atoms with thermal energy are injected into a deuterium plasma where polarized protons or negative hydrogen ions are formed due to the quasi-resonant charge-exchange reaction:

Ionization of polarized atoms Resonant charge-exchange reaction is charge exchange between atom and ion of the same atom: A 0 + A + →A + + A 0 cross -section is of order of cm 2 at low collision energy Charge-exchange between polarized atoms and ions of isotope relative the polarized atoms to reduce unpolarized background W. Haeberli proposed in 1968 an ionizer with colliding beams of ~1-2 keV D - ions and thermal polarized hydrogen atoms: H 0 ↑+ D − ⇒ H − ↑+ D 0

Cross-section vs collision energy for process H  + H 0  H 0 + H   = cm 2 at ~10eV collision energy

Destruction of negative hydrogen ions in plasma H  + e  H 0 + 2e  ~ 4  cm 2 H  + D +  H 0 + D 0  ~ 2  cm 2 H  + D 0  H 0 + D   ~ cm 2 H  + D 2  H 0 + D 2 + e  ~ 2  cm 2 H  + D 0  HD 0 + e  ~ cm 2

Details of ABIS with Resonant Charge Exchange Ionization

Resonance charge exchange ionizer with two steps surface plasma converter Jet of plasma is guided by magnetic field to internal surface of cone; fast atoms bombard a cylindrical surface of surface plasma converter initiating a secondary emission of negative ions increased by cesium adsorption.

Probability of H - emission as function of work function (cesium coverage) The surface work function decreases with deposition of particles with low ionization potential and the probability of secondary negative ion emission increases greatly from the surface bombarded by plasma particles. Muons, Inc. 25

INR ABIS: Oscilloscope Track of Polarized H- ion Polarized H- ion Current 4 mA (vertical scale- 1mA/div) Unpolarized D- ion current 60 mA (10mA/div) A. Belov

Main Systems of INR ABIS with Resonant Charge Exchange Ionization Muons, Inc.

The pulsed polarized negative ion source (CIPIOS) multi-milliampere beams for injection into the Cooler Injector Synchrotron (CIS). Schematic of ion source and LEBT showing the entrance to the RFQ. The beam is extracted from the ionizer toward the ABS and is then deflected downward with a magnetic bend and towards the RFQ with an electrostatic bend. This results in a nearly vertical polarization at the RFQ entrance. Belov, Derenchuk, PAC 2001

INJECTION OF BACKGROUND GAS AT DIFFERENT POSITION ATTENUATION OF THE BEAM IS DEPENDENT FROM THE POSITION OF THE GAS INJECTIOJN NOT MANY EXPERIMENTAL DATA AVAILABLE D.K.Toporkov, PSTP-2007, BNL, USA

Cryogenic Atomic Beam Source Liquid nitrogenCryostat Two group of magnets – S1, S2 (tapered magnets) and S3, S4, S5 (constant radius) driven independently, 200 and 350 A respectively BINP atomic beam source with superconductor sextupoles

Focusing magnets Permanent magnets B=1.6 T Superconducting B=4.8 T       sr  rad   sr  rad

Zelenski OPPIS : Zelenski, Mori et al. 20 years of development 1.6 mA H -  85-90% Polarization with new proton source 20-50mA possible L.W. Anderson (Wisconsin) - optically pumped Na as donor (1979) 3 keV H + POLARIZED H + AND H - DONOR: OPTICALLY PUMPED CHARGE EXCHANGE BB “SONA” TRANSITION W. Haeberli, PSTP-2007, BNL, USA

BNL OPPIS, A. Zelenski

A general polarized RHIC OPPIS injector layout. ECR: electron-cyclotron resonance proton source in SCS; SCS: superconducting solenoid; Na-jet: sodium-jet ionizer cell; LSP: Lamb-shift polarimeter; M1, M2: dipole bending magnets.

Advanced OPPIS with high brightness BINP proton injector 1- proton source; 2- focusing solenoid; 3- hydrogen neutralizing cell; 4- superconducting solenoid; 5- helium gas ionizing cell; 6- optically pumped Rb vapor cell; 7- deflecting plates; 8- Sona transition region; 9- sodium ionizer cell; 10- pumping lasers; PV- pulsed gas valves.

Enhanced OPPIS with BINP injector

BINP Injector for OPPIS

Realistic Extrapolation for Future ABS/RX Source: H- ~ 10 mA, 1.2 π·mm·mrad (90%), Pz > 95% D- ~ 10 mA, 1.2 π·mm·mrad (90%), Pzz > 95% OPPIS: H- ~ 40 mA, 2.0 π·mm·mrad (90%), Pz ~ 90% H+ ~ 40 mA, 2.0 π·mm·mrad (90%), Pz ~ 90% OPPIS intensity can be higher, but Polarization in ABS/RX Source can be higher because ionization of polarized atoms is very selective and molecules do not decrease polarization. Muons, Inc.

3 He ++ Ion source with Polarized 3 He Atoms and Resonant Charge Exchange Ionization A.S. Belov, PSTP-2007, BNL, USA

Cross-section vs collision energy for process He ++ + He 0 →He 0 + He ++ σ=5 ⋅ 10-16cm 2 at ~10eV collision energy A.S. Belov, PSTP-2007, BNL, USA

Polarized 6Li+++ Options and other elements with low ionization potential Existing Technology: Create a beam of polarized atoms using ABS Ionize atoms using surface ionization on an 1800 K Tungsten (Rhenium) foil – singly charged ions of a few 10 ’ s of µ A Accelerate to 5 keV and transport through a Cs cell to produce negative ions. Results in a few hundred nA ’ s of negative ions (can be increased significantly in pulsed mode of operation) Investigate alternate processes such as quasiresonant charge exchange, EBIS ionizer proposal or ECR ionizer. Should be possible to get 1 mA (?) fully stripped beam with high polarization Properties of 6Li: Bc= 8.2 mT, m/mN= , I = 1 Bc = critical field m/mN= magnetic moment, I = Nuclear spin Muons, Inc.

Production of highest polarization and reliable operation are main goals of ion sources development in the Jefferson Lab Development of Universal Atomic Beam Polarized Sources (most promising, less expensive for repeating). It is proposed to develop one universal H-/D-/He ion source design which will synthesize the most advanced developments in the field of polarized ion sources to provide high current, high brightness, ion beams with greater than 90% polarization, good lifetime, high reliability, and good power efficiency. The new source will be an advanced version of an atomic beam polarized ion source (ABPIS) with resonant charge exchange ionization by negative ions, which are generated by surface-plasma interactions. Muons, Inc.

Ion Sources for Electron Ion Colliders Optimized versions of existing polarized ion sources (ABPS and OPPIS) and advanced injection methods are capable to delivery ion beam parameters necessary for Projected high luminosity of EIC. Good luck for Slava & Ko to reach this outstanding goals. Muons, Inc.