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A novel polarization technique had been successfully implemented for the RHIC polarized H− ion source upgrade to higher intensity and polarization. In this technique a proton beam inside the high magnetic field solenoid is produced by ionization of the atomic hydrogen beam (from external source) in the He-gas ionizer cell. Further proton polarization is produced in the process of polarized electron capture from the optically-pumped Rb vapour. The use of high-brightness primary beam and large cross-sections of charge-exchange cross-sections resulted in production of high intensity H− ion beam of 85% polarization. High beam brightness and polarization resulted in 75% polarization at 23 GeV out of AGS and 60-65% beam polarization at 100-250 GeV colliding beams in RHIC. The status of un-polarized magnetron type (Cs-vapour loaded) BNL source is also discussed.

Two volume sources equipped with DESY and CERN plasma generators and a low voltage electron dump were operated at 45 kV in the Linac4 tunnel and on a dedicated test stand. These volume sources delivered approximately 20 mA and ensured the commissioning of the Radio Frequency Quadrupole accelerator and of the first section of the Drift Tube Linac. CERN’s prototype of a cesiated surface source equipped with this electron dump was operated continuously from November 2013 to April 2014 on the ion source test stand and is being commissioned in the Linac4 tunnel. Before cesiation, the prototype conditioned in volume mode provided up to 30 mA H− beam. Short cesiations, of the order of 10 mg effectively reduced the intensity of co-extracted electrons down to 2 - 8 times the H− current; this cesiated surface operation mode delivered up to 60 mA H− beam. An H− beam of the order of 40 mA was sustained up to four weeks operation with 500 μs pulses at 1.2s spacing. A new extraction was designed to match these beam pro...

In Optically Pumped Polarized Ion Sources (OPPIS), the atomic beam is first electron polarized, and then this polarization is transferred to the nucleus by a suitable perturbing magnetic field. In the BNL OPPIS, the electron polarized atomic beam experiences the perturbing field when it traverses a region where the axial magnetic field reverses direction in a controlled manner—strength and gradient. This is the so‐called Sona Transition region, named after P. G. Sona, who first suggested the technique. We have extensively studied how the magnetic field profile in the Sona region affects beam polarization. In these studies, we have observed oscillations in polarization for certain field profiles, and tried explain them. We report on these studies.

Methods of producing the nuclear polarized 3He+ ions and their ionization to 3He++ in ion trap of the electron Beam Ion Source (EBIS) are discussed. Computer simulations show that injection and accumulation of 3He+ ions in the EBIS trap with slanted electrostatic mirror can be very effective for injection times longer than the ion traversal time through the trap.

The depolarization factors in the multi‐step spin‐transfer polarization technique and basic limitations on maximum polarization in the OPPIS (Optically‐Pumped Polarized H− Ion Source) are discussed. Detailed studies of polarization losses in the RHIC OPPIS and the source parameters optimization resulted in the OPPIS polarization increase to 86–90%. This contributed to increasing polarization in the AGS and RHIC to 65∼70%.

The depolarization factors in the multi‐step spin‐transfer polarization technique and basic limitations on maximum polarization in the Optically‐Pumped Polarized H‐ Ion Source (OPPIS) are discussed. Results of simulations and experimental studies of the Sona‐transition polarization transfer process are presented. The experimentally observed polarization oscillations and polarization maximum peak were reproduced in simulations. Detailed studies of polarization losses in the RHIC OPPIS and the source parameters optimization resulted in the OPPIS polarization increase to 86–90%. This contributed to increasing polarization in the AGS and RHIC to 65∼70%.

We discuss the beam polarization measurement strategy at RHIC with achieved relative precision of better than 5%.

The RHIC polarized proton collider polarimeters employ the analyzing power in p‐Carbon elastic scattering in the Coulomb Nuclear Interference region to measure the proton beam polarization. These are calibrated by the polarized hydrogen jet target that measures the absolute beam polarization utilizing the pp elastic scattering process in the CNI region. This paper describes the status of these polarimeters and the efforts employed to improve the performance in terms of better resolution, rate handling capability, and reduced systematic uncertainties.

A dual partial snake scheme has been used for AGS polarized proton operation for several years. It has provided polarized proton beams with 1.5×1011 protons per bunch and 65% polarization for the RHIC spin program. There is still residual polarization loss due to both snake resonances and horizontal resonances as shown in the data. Several schemes were tested or proposed in the AGS to mitigate the loss, such as putting horizontal tune into the spin tune gap, injection into a accelerating bucket, and tune jump across the horizontal resonances. This paper presents the experiment and simulation results and analyses.

During Run‐8, the Relativistic Heavy Ion Collider (RHIC) provided collisions of spin‐polarized proton beams at two interaction regions. Physics data were taken with vertical orientation of the beam polarization, which in the “Yellow” RHIC ring was significantly lower than in previous years. We present recent developments and improvements as well as the luminosity and polarization performance achieved during Run‐8, and we discuss possible causes of the not as high as previously achieved polarization performance of the “Yellow” ring.

Recent progress in polarized ion sources development is reviewed. New techniques for production of polarized H− ion (proton), D− (D+) and 3He++ ion beams are discussed. Feasibility studies of these techniques are in progress at BNL and other laboratories. Polarized deuteron beams will be required for the polarization program at the Dubna Nuclotron and at the deuteron Electric Dipole Moment experiment at BNL. Experiments with polarized 3He++ ion beams are a part of the experimental program at the future Electron Ion Collider.

The electron ion collider (EIC) has been recently identified by the US nuclear physics community in its long range plan, to be the most important future experimental facility for the precision study of QCD and the spin structure of the nucleon. While the physics of this is exciting and compelling, the technology that needs to be developed to realize the science remains challenging. Several items have been identified which will need R&D and will be pursued in the near future. Measurement of lepton and hadron or light nuclear beam polarization is one of those daunting tasks, which need immediate and high level of attention to completely realize the promised science of the EIC. This article will summarize the science goals and identify the polarimetry and some other detector related challenges posed by this next generation QCD facility.

Solid NH3 and ND3 provide a highly polarizable, radiation resistant source of polarized protons and deuterons and have been used extensively in high luminosity experiments investigating the spin structure of the nucleon. Over the past twenty years, the UVA polarized target group has been instrumental in producing and polarizing much of the material used in these studies, and many practical considerations have been learned in this time. In this discussion, we analyze the polarization performance of the solid ammonia targets used during the recent JLab Eg4 run. Topics include the rate of polarization decay with accumulated charge, the annealing procedure for radiation damaged targets to recover polarization, and the radiation induced change in optimum microwave frequency used to polarize the sample. We also discuss the success we have had in implementing frequency modulation of the polarizing microwave frequency., 5 pages, 6 figures. XIIth International Workshop on Polarized Sources, Targets and Polarimetry

Analysis of the beam intensities from the atomic beam sources (ABS) are reviewed. This analysis shows that the intensity of the beams is saturated in the range of 1017 at/sec. The highest intensity of the polarized hydrogen beam obtained in the RHIC ABS and was found to be 1.2*1017 at/sec. Some possible reasons for the atomic beam intensity limitation such as beam formation model, intra beam scattering, background vacuum conditions, presence of the skimmers etc. are discussed. Some additional measurements are suggested to provide more complete understanding of the atomic beam formation and possible beam intensity improvement.

Ion back‐bombardment is the dominant mechanism that limits the operating lifetime of DC high voltage GaAs photoelectron guns. In this work, an electrically isolated anode electrode was used to distinguish the QE damage contributions of ions produced within the cathode/anode gap and those produced downstream of the anode. This new anode design provides a means to suppress QE decay due to ionized gas in the beam line.

The methods of dynamically polarizing nuclei (DNP) have not only lead to the development of increasingly sophisticated polarized targets with which the role of spin in nuclear and particle interactions is investigated, but have also opened new possibilities in neutron science by exploiting the strong spin dependence of the neutron scattering. Very recently NMR and MRI have been a driving force behind a surge of interest in DNP methods, considering its tremendous potential for sensitivity enhancement. An overview of our current projects with dynamically polarized nuclei is given.

This paper was part of the general‐interest session on lecture day, and is thus addressed to a general audience. A 50‐year historic overview of the development of the tools of proton spin physics is presented: nuclear scattering, ion sources for polarized protons and deuterons based on atomic beam and optical pumping methods, and polarized gas targets.

We propose a novel scheme to realize ultrafast nuclear spin polarization by short laser pulses. Combined use of the hyperfine interaction and the static electric field is the key for that. The idea is specifically applied to various isotopes of alkaline‐earth atoms, Mg and Ca, with nuclear spin I = 1/2, 3/2, 5/2, and 7/2. After the detailed theoretical analysis, we find that spin‐polarization as high as 88%, 66%, 33%, and 25%, respectively, for I = 1/2, 3/2, 5/2, and 7/2, can be attained in the time scale of a few to tens of ns, which is at least 2–3 orders of magnitude shorter than any known optical methods. Due to this ultrafast nature, our scheme is applicable not only for stable nuclei but also unstable nuclei with a lifetime as short as a few μs.

We have developed a precision NMR polarimeter to observe the proton and deuteron polarization of a frozen spin HD target used in photoproduction experiments at the LEGS facility. This polarimeter uses a pair of magnetically orthogonal (“crossed”) RF coils to reduce the signal to very small levels in the absence of polarization of the sample. This reduces the thermal noise in the total signal with polarization, which improves the statistical precision of the polarization determination. Care has been taken in the design of the instrument to reduce nonthermal sources of noise, with the result that a fractional polarization uncertainty of 4% can be maintained over the lifetime of the targets, which has been as long as 19 months. The non‐ideal response of the NMR circuit makes a negligible contribution to this uncertainty.

Resonance enhancement of the quantum efficiency of new polarized electron photocathodes based on a short‐period strained superlattice structures is reported. The superlattice is a part of an integrated Fabry‐Perot optical cavity. We demonstrate that the Fabry‐Perot resonator enhances the quantum efficiency by the order of magnitude in the wavelength region of the main polarization maximum. The high structural quality implied by these results points to the very promising application of these photocathodes for spin‐polarized electron sources.

In the framework of the FAIR project [1], the PAX collaboration [2] has suggested new experiments using polarized protons and antiprotons. In order to provide polarized antiprotons, the polarization buildup by spin‐dependent attenuation due to nuclear interaction (spin‐filtering) must be studied. The goal of these investigations is to understand the physics of the spin‐filtering process with stored protons at COSY, and to shed light on the role of polarized electrons for the polarization buildup. Later on, the spin‐dependence of the proton‐antiproton interaction will be investigated at the Antiproton Decelerator ring (AD) of CERN. In order to carry out these investigations, a storage ring section has to be developed which minimizes the spin‐independent losses due to single Coulomb scattering.

During the 1990s, at numerous facilities world wide, extensive R&D devoted to constructing reliable GaAs photoguns helped ensure successful accelerator-based nuclear and high-energy physics programs using spin polarized electron beams. Today, polarized electron source technology is considered mature, with most GaAs photoguns meeting accelerator and experiment beam specifications in a relatively trouble-free manner. Proposals for new collider facilities however, require electron beams with parameters beyond today's state-of-the-art and serve to renew interest in conducting polarized electron source R&D. And at CEBAF/Jefferson Lab, there is an immediate pressing need to prepare for new experiments that require considerably more beam current than before. One experiment in particular?Q-weak, a parity violation experiment that will look for physics beyond the Standard Model?requires 180 uA average current at polarization >80% for a duration of one year, with run-averaged helicity correlate

Proton polarimetry at RHIC uses the interference of electromagnetic (EM) and hadronic scattering amplitudes. The EM spin‐flip amplitude for protons is responsible for the proton's anomalous magnetic moment, and is large. This then generates a significant analyzing power for small angle elastic scattering. RHIC polarimetry has reached a 5% uncertainty on the beam polarization, and seems capable of reducing this uncertainty further. Polarized neutron beams are also interesting for RHIC and for a polarized electron‐polarized proton/ion collider in the future. In this case, deuterons, for example, have a very small anomalous magnetic moment, making the approach used for protons impractical. Although it might be possible to use quasi‐elastic scattering from the protons in the deuteron to monitor the polarization. 3‐He beams can provide polarized neutrons, and do have a large anomalous magnetic moment, making a similar approach to proton polarimetry possible.

Polarized electron sources have been actively developed since about 1960. Six separate methods have been developed to provide useful polarized beams. We review the underlying physics and the history surrounding the development of these sources.

This is a review of the physics underlying both why polarized targets and beams of 3He nuclei are interesting for experiments, and how such beams and targets are realized. A summary is given of the variety of methods used, with experimental examples to illustrate both historical developments and current achievements. A brief look at systems proposed or being planned for the future is also included.

Neutron scattering is one of the most important tools for materials research. However, neutrons are very expensive to produce. Even with the best sources, such as the newly completed Spallation Neutron Source at the Oak Ridge National Laboratory, most neutron scattering experiments are still flux limited. One way to improve the experimental data is polarized neutron scattering from polarized solid target: the strong spin‐dependent neutron scattering cross‐section can increase the coherent scattering and decrease the incoherent scattering at the same time, thereby significantly enhancing the signal to noise ratio. Hydrogen, abundant in most soft condensed matters, has a strong spin‐dependent scattering cross‐section. Early applications of polarized neutron scattering in biological soft condensed matters [1] have already demonstrated the huge potential of this technique [2]. Here we describe the polarized target program at the SNS. The program is under active construction and is aimed at serving neutron scattering at the SNS.

The development of polarized electron sources in the 1970s capable of generating beams for injection into electron accelerators has been a major enabling factor for spin physics with electrons during the past quarter century. These sources continue to be refined for higher polarization and better operability. Recent developments were presented at this workshop in both plenary sessions and in 2 separate parallel sessions. The ILC plans to utilize not only a polarized electron source but also a polarized positron source. The current state of two types of positron sources were presented. This paper is a brief summary of all of these presentations.

The theoretical prediction for the polarizing cross section when scattering antiprotons off polarized e+ amounts to 2.1013 barn at 1.7 keV hadron energy in the e+ rest frame. Under this conditions polarizing stored antiprotons in a cooler‐like arrangement becomes feasible. Compact e+ sources of sufficient intensity can be provided with present day technology in order to achieve a polarization of Pp¯ = 0.17 for 1010 stored antiprotons within one hour. Positron storage ring based designs offer an enormous increase in intensity, making an efficient polarizer feasible, even if the cross sections are many orders of magnitude smaller than presently predicted.

By advancing the components of the polarized negative ion source the number of polarized particles for injection into the cyclotron injector of the cooler synchrotron COSY at the IKP of the Forschungszentrum Julich has been increased, since 2000, by a factor of three to 5.5×1012 H− ions, delivered in a 20 milliseconds pulse with a repetition rate of 2 seconds. This report sums up briefly the characteristics of the ion source in its present mode of operation and describes the achievements towards higher beam intensities as well as for providing polarized H− and D− beams with high reliability.

Spin‐polarized radioactive ion beams are produced in the projectile fragmentation reaction induced by intermediate‐energy heavy ion beams. The degree of spin polarization shows characteristic dependence on the outgoing momentum of the projectile fragment in the magnitude around 1∼10%. The qualitative behavior is well described by the kinematical model of the fragmentation process. Recently, we have successfully produced spin‐polarized beams of aluminum isotopes in the mass A∼30 region via the fragmentation of 95 MeV/u 40Ar projectiles. The magnetic moments of 30Al and 32Al and the electric quadrupole moments of 31Al and 32Al have been measured using the β‐NMR technique with the polarized RI beams of the Al isotopes.

MIT‐Bates, in collaboration with BNL, plans to investigate the possibility of building a very high intensity polarized electron source suitable for a linac‐ring version of eRHIC. The main challenges in this project are very high average and peak current and high heat load on the cathode. The planned ways to overcome these problems are discussed.

By making use of previous analysis of CNI for pp and pC scattering, the spin-flip factor for np scattering is determined as a function of energy and then used to calculate the p He3 asymmetry A_N(s)' arising in p He 3 elastic scattering. It is found to be comparable to A_N(s) for pp scattering, but of the opposite sign. It seems that this method could be a practical for measuring the polarization of a He3 beam.

In order to study the spin structure of the neutron at high energy, a beam rich in polarized neutrons needs to be developed. The neutron has no charge and cannot be accelerated, so either deuterons or helions must be considered. When it comes to spin manipulation and stability of the polarization in a circular accelerator, it is the anomalous part of the magnetic moment which is important. If the anomaly is too small, then manipulation becomes difficult as in the case of deuterons—spin rotators and Siberian snakes become ineffective. 3He nuclei appear to be the easiest choice for a polarized neutron beam. In this paper I discuss the prospects for both helions and deuterons as polarized beams in RHIC or in an electron‐ion collider.

Numerical integration of Shroedinger equations is used for study of adiabaticity of spin motion of hydrogen atoms in changing magnetic fields. For hydrogen atoms of thermal energies, adiabaticity of spin motion is preserved in a wide range of magnetic field amplitudes larger than 0.1 G. Adiabatic RF transitions used in atomic beam–type sources and Sona‐type transitions used in OPPIS are simulated.