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We present an efficient method for polarized 963 nm emission based on second-harmonic generation from a high-power, polarized thulium-doped fiber laser using periodically poled MgO:LiNbO3 as the nonlinear material. The maximum 963-nm output power of 710 mW has been achieved with a pulse duration of 34 ns at the repetition rate of 100 kHz and a Gaussian spatial beam profile. The frequency doubling efficiency is up to 56%, and the total optic-to-optic conversion efficiency is more than 12.9%. In addition, third- and fourth-harmonic generations have been observed. [ABSTRACT FROM AUTHOR]

Polarized targeting and deposition of MT1-MMP is pivotal for metastasis. In this issue of Developmental Cell , Wang et al. (2017) reveal that a signaling molecule generated by phospholipase D2 drives deposition of MT1-MMP at the site of invadopodia formation and is critical for metastasis in a transgenic breast cancer model. [ABSTRACT FROM AUTHOR]

Abstract: Measurement of circular polarization of gamma-rays with position sensitive solid state detectors is proposed. It is based on the transfer of the photon spin to the recoiled electron in the process of Compton scattering and subsequent detection of the electron spin polarization. Bremsstrahlung polarization correlations, in particular the left–right asymmetry of the photon emission from transversally polarized electrons, are used for this purpose. Compton scattering and electron bremsstrahlung events as well as the scattered and the bremsstrahlung photon absorptions take place inside the active volume of the position sensitive detector. These events are identified and their complete kinematics is reconstructed by means of gamma-ray tracking. No spin polarized targets and no inactive materials are needed for this technique. The proposed method is naturally integrated into the concept of a Compton telescope, allowing for the first time to build an imaging gamma-ray circular polarimeter. It should work in the energy region of several 100keV up to several 10MeV. [Copyright &y& Elsevier]

Abstract: Polarized from metastability exchange optical pumping (MEOP) is used as an effective polarized neutron target for electron scattering experiments at the MAinz MIcrotron (MAMI). With the present setup an initial polarization of up to 72% has been obtained at the experimental area. A novel calibration technique will be presented which allows the determination of the absolute polarization within a relative uncertainty of 3%. [Copyright &y& Elsevier]

Abstract: A frozen-spin- polarized deuteron target cooled by the 3He/4He dilution refrigerator is described. Fully deuterated 1,2-propanediol was used as a target material. Deuteron vector polarization about 40% was obtained for the target in the shape of a cylinder of 2-cm diameter and 6-cm length. The target is intended for a study of 3N interactions at the polarized neutron beam generated by the Van de Graaff accelerator at the Charles University in Prague. [Copyright &y& Elsevier]

The factors are reviewed that can affect the systematic uncertainties in CW-NMR measurements of the polarization in solid state polarized targets. The main problem with large signals, typically obtained with protons, is non-linearity arising from failure of the constant RF drive current assumption. The non-linearity can be reduced by operation at lower than normal signal levels. With the much smaller size deuteron signals, a limiting factor may be the instability of the background signal generated by the resonant length cable, used in the standard system. A new system is demonstrated, using non-resonant length cables, which is expected to reduce these uncertainties to a low level. [Copyright &y& Elsevier]

A polarized deuterium target was developed for the use of the first measurement of the so-called complete spin dependent cross-sections of the &Drarr;(↘,p)T nuclear reaction at 20 MeV. In order to minimize the energy losses of incident and emitted particles in the target materials, the target thickness should be as thin as possible. A deuterated polyethylene foil of 30–50 μm thickness was used as polarized target. The deuterons contained in the foil are polarized by the dynamic nuclear polarization method in the magnetic field of 2.5 T. The polarized deuterium target system has been installed in the 1st experimental hall of the Tandem Accelerator Center at the University of Tsukuba. From the target asymmetry measurement of &Drarr;(d,d)D elastic scattering by a 20 MeV deuteron beam about 10% deuteron target polarization was confirmed. [Copyright &y& Elsevier]

An experimental program has been started at MAMI and ELSA to measure the integrand of the Gerasimov–Drell–Hearn sum rule (GDH) in a photon energy range starting from the pion threshold up to 2.9 GeV. A polarized target has been built, which is based on the frozen spin technique. Since the value of the nucleon polarization and the areal density of the target contribute directly to the result of the GDH-integral both quantities have to be determined with high accuracy. [Copyright &y& Elsevier]

Experience with polarized targets and the achievement of very low temperatures at the Laboratory of Nuclear Problems (JINR, Dubna) and at other places have triggered the idea of using a radically new technique based on dissolving 3He in 4He to create a frozen spin polarized target. The short history of the development of such proton and deuteron targets at the LNP is given. Diols with the complex Cr(V) are used as target materials. A characteristic feature of these targets is the long relaxation time (≈1000 h) in magnetic fields of about 0.5 T. Lately, the Saclay–Argonne frozen spin polarized proton target used initially in the E704 experiment at FERMILAB has been upgraded by adding the missing parts. A first physics experiment has been carried out. [Copyright &y& Elsevier]

We present the results of our investigation of a series of internal holding magnets for longitudinal and transverse polarizations. These magnets will be placed inside a polarizing refrigerator designed for frozen spin targets. The studied magnets will provide the holding field in the range 0.3–0.5 T. The total thickness of the superconducting coils is of the order 0.5 mm. The frozen spin target is under construction for use in photo-nuclear experiments in concert with the JLAB Hall-B CLAS detector. [Copyright &y& Elsevier]

A polarized proton solid target has been developed at the Center for Nuclear Study, the University of Tokyo. The polarized target makes use of a large population difference among Zeeman sub-levels in the photo-excited triplet state of pentacene. We have successfully applied this polarized target to the first RI beam experiment, where a vector analyzing power for the proton-6He elastic scattering has been measured. [Copyright &y& Elsevier]

Double polarization experiments at the Laser Electron Gamma Source (LEGS) at Brookhaven National Laboratory have been performed with polarized photon beams and a polarized Hydrogen Deuteride (HD) frozen spin target. After polarizing at 15 T and 17 mK and subsequently reaching a frozen spin mode, a target was cold extracted (at 2.5 K and 0.016 T) and installed into an In-Beam Cryostat (IBC) which held the target at 0.7 T and 1.25 K. In-beam relaxation times of 13 days for polarized hydrogen and 36 days for polarized deuterium have been measured. Data were taken with 30% polarized-H and 6% polarized-D, although higher polarization levels have been achieved. Several new improvements are being implemented to improve the operating parameters of polarized HD targets. These include the fabrication of a vibration isolator to lower the polarizing temperature, the purchase of a new IBC to reach longer in-beam relaxation times with higher field and lower temperature (1 T and 200 mK), the construction of a new cold transfer cryostat with a higher field (0.13 T) to reduce polarization loss during target transfers, and the installation of a much improved NMR system for polarization calibration and online monitoring. A summary of the existing data, the ongoing modifications and projection for future performance will be discussed. [Copyright &y& Elsevier]

A method to generate strongly polarized nuclear spins in solution has been developed, using Dynamic Nuclear Polarization (DNP) at a temperature of 1.2 K, and at a field of 3.354 T, corresponding to an electron spin resonance frequency of 94 GHz. Trityl radicals are used to directly polarize 13C and other low-γ nuclei. Subsequent to the DNP process, the solid sample is dissolved rapidly with a warm solvent to create a solution of molecules with highly polarized nuclear spins. Two main applications are proposed: high-resolution liquid state NMR with enhanced sensitivity, and the use of the hyperpolarized solution as an MR imaging agent. [Copyright &y& Elsevier]

The molecular hydrogen isotopes contain no unpolarisable background. From this point of view they appear to be the material of choice for a polarised bulk target in scattering experiments. The fast nuclear relaxation of H2 and D2 is one reason that these substances are not highly polarisable. This fact brings hydrogendeuteride (HD) into focus. In Bochum a device to freeze out gases into the consisting 4He-cryostat has been built up. The principle of the Dynamic Nuclear Polarisation requires a sufficient amount of paramagnetic electrons. These have been produced by cracking HD molecules at 1 K using a 90Sr β-source with an activity of 3.7 GBq. Six days of effective irradiation resulted in a density of paramagnetic centres in the order of 1018 spins/cm3. This could be estimated from bolometric electron paramagnetic resonance (EPR) measurements. Dynamic polarisation could not be achieved. This is accounted to isotopic impurities in the used HD, which accelerate the nuclear relaxation. The constant of ortho–para conversion in H2 could be confirmed to be 1.9%/h. [Copyright &y& Elsevier]

The dynamic nuclear polarization (DNP) of 6LiD requires 1 mW/g or more microwave power in the beginning of the process. With the material of 350 g, this gives more than 350 mW in total for the COMPASS polarized target. A temperature around 300 mK or below is needed for an efficient polarization. These low temperatures can only be achieved with a dilution refrigerator designed to operate with a 3He flow of 100 mmol/s. In order to keep the polarization in the frozen mode, temperatures of about 65 mK are used with typical magnetic relaxation times of more than 1400 h at 0.42 T and of more than 15 000 h at 2.5 T. Low lattice temperature is important in achieving high nuclear polarization. The base temperature is limited by the heat brought to the mixing chamber by the inlet 3He and by radiation and conduction of heat. [Copyright &y& Elsevier]

Continuous wave nuclear magnetic resonance (NMR) is used to determine the target polarization in the COMPASS experiment. The system is made of the so-called Liverpool Q-meters, Yale-cards, and VME modules for data taking and system controlling. In 2001 the NMR coils were embedded in the target material, while in 2002 and 2003 the coils were mounted on the outer surface of the target cells to increase the packing factor of the material. Though the error of the measurement became larger with the outer coils than with the inner coils, we have performed stable measurements throughout the COMPASS run time for 3 years. The maximum polarization was +57% and -53% as the average in the target cells. [Copyright &y& Elsevier]

The dilution refrigerator used to cool the large COMPASS polarized target is monitored through a PC running LabVIEWTM 6.1 under Windows 2000TM. About 60 parameters of the target (temperatures, pressures, flow rates) are continuously plotted and checked. They are periodically recorded in an OracleTM database and in a data file. An alarm for every parameter can be individually activated and optionally connected to a GSM (Global System for Mobile Communication) delivery message system. A web server receives and publishes the online status of the target with online tables and graphics on a dedicated COMPASS polarized target information web site. A Siemens programmable logic controller (PLC) powered by an uninterruptable source keeps the cryogenic system safe and stable during the long beam periods by controlling valves and interlocks. This safety feature protects the dilution refrigerator against potential damages in case of power failure. [Copyright &y& Elsevier]

Here we will give an overview of the developments in cryogenic and magnet technology used in polarized targets from the roots to nowadays and a brief outlook on new concepts of the polarized target technology for future polarized nuclear and particle physics experiments. [Copyright &y& Elsevier]

We have experimentally studied the first and the second moments of D, 6Li and 7Li (I>1/2) NMR lines in a granulated LiD-target material as a function of nuclear polarizations and the data has been compared with a theory elaborated by Abragam, Roinel and Bouffard for monocrystalline samples. The experiments were carried out in the large COMPASS twin-target at CERN. The static local magnetic field of the polarized nuclei was measured by frequency shift between the NMR-signals in the two oppositely polarized cells and lead to the first moment, whereas the investigation of the second moment was done through Gaussian approximation. The average field magnitude in granulated material was estimated 20% larger than the value given by the calculations for monocrystalline samples of cylindrical shape. The second moment shows a qualitative agreement with the theory but it is slightly larger at the negative than at the positive polarization. In a polarized mode, the moments depend on the saturated microwave field. [Copyright &y& Elsevier]

Due to the vanishing quadrupole interaction only a single narrow 2.8 kHz full-width half-maximum nuclear magnetic resonance (NMR) line is observed in the 6LiD target material for deuterium and 6Li with spin 1. The second and fourth moments are obtained from a Memory function fit to the measured NMR signal. The values are compared to the calculations from dipole interaction between nuclei. The NMR line shape during polarization up to +55% and -52% is discussed. [Copyright &y& Elsevier]

In terms of dynamic nuclear polarization (DNP) studies and systematic target material research it is crucial to know the EPR lineshape of the DNP relevant paramagnetic centers. Therefore in Bochum an EPR spectrometer has been implemented into the 4He evaporation DNP facility in order to perform EPR studies at DNP conditions (B=2.5 T, T=1 K). The spectrometer hardware and performance as well as first results are presented. [Copyright &y& Elsevier]

In the past 3 years a series of experiments have shed new light on the mechanism of dynamic nuclear polarisation (DNP). Time-resolved polarised small-angle neutron scattering and nuclear magnetic resonance have been used simultaneously to study the nuclear polarisation build-up around paramagnetic centres during DNP. This approach, which aims at visualising the nuclear polarisation process on a microscopic scale, shall be exemplified and the experimental techniques used described in some detail. [Copyright &y& Elsevier]

Many free radicals were added to organic compounds in search of high proton and deuteron polarizations. Few found practical application. A short review is presented, and special attention is given to some stable nitroxyl radicals which have lately been admixed to organic compounds solid at room temperature, in particular to scintillators. [Copyright &y& Elsevier]

For a proposed high-accuracy measurement of the spin-dependent neutron scattering length of the deuteron, a precise relative knowledge of the polarization of the proton and deuteron spin systems in the target material is needed. A simulation of the Q-meter system has been performed to get a quantitative estimate of the influence of various causes on the determination of the signal integral. Experimental and theoretical line shapes have been used as input to the model circuit. The response, i.e. the signal output, has been treated in a realistic way (e.g. integral determination, residual baseline fitting) and the effect of circuit parameter drifts has been analyzed. Several Q-meter system setups and measurement modes have been investigated with respect to inherent limitations and sensitivity to parameter drifts. [Copyright &y& Elsevier]

Solid state polarised targets have been in use in both particle and nuclear physics experiments for nearly 40 years. The vast majority of these experiments have used the continuous wave (CW) NMR technique to measure the target polarisation. The development of this technique over this time period is presented. [Copyright &y& Elsevier]

The Polarized Target Group at the University of Virginia has conducted experiments at both the Stanford Linear Accelerator Center (SLAC) and the Thomas Jefferson National Accelerator Facility (JLab) in which a high-intensity (100 nA) electron beam was focused on a polarized target of solid ammonia and/ or solid, deuterated ammonia. Analysis of the target polarization data have revealed several unique characteristics of ammonia. Topics discussed include the rate of polarization decay with accumulated charge, methods of recovering polarization through target annealing and damage-induced shifts in the optimum microwave frequency used to drive the polarization. [Copyright &y& Elsevier]

The enormous efforts towards dynamically polarized ammonia and deuterated ammonia (d-ammonia) with their reasonable high polarizable nucleon contents (quality factor) are reviewed. The early attempts are also a story of failures until a radiation doping method for NH3 was successfully demonstrated in the end of the 1970s. Some years later the outcome of intense studies and new developments (with pitfalls, too) was the availability of the highly polarizable target materials 14NH3, 15NH3, 14ND3 and 15ND3, all of them doped for the dynamic nuclear polarization (DNP) by radiation. These materials have been used in new particle physics experiments which, up to that time, suffered either from the lower quality factors or from the modest polarization resistance against radiation damage of the existing alcohol and diol target materials. [Copyright &y& Elsevier]

We describe the design, construction, and performance of a polarized solid target for use in electron scattering experiments with the CEBAF Large Acceptance Spectrometer. Protons and deuterons are continuously polarized by microwave-induced spin–flip transitions at 1 K and 5 T. The target operated successfully during two cycles in 1998 and 2000, providing proton and deuteron polarizations as high as 96% and 46%, respectively. The unique features of the target which permit its use inside a 4π spectrometer are stressed. Comparison is made between the target polarization measured by the traditional method of NMR and by electron elastic scattering. [Copyright &y& Elsevier]

The COMPASS (NA58) experiment at CERN operates with a large solid polarized target (PT) to study the spin structure of the nucleon. The COMPASS PT system started its operation with the target material 6LiD in 2001. Deuteron polarizations of +54.2% and −47.1% were achieved in a 3He/4He dilution refrigerator at a magnetic field of 2.5 T. The equal spin temperature (EST) concept was found to hold among the deuteron, the 6Li and the 7Li nuclei during the dynamic nuclear polarization (DNP) process. The agreement with the EST concept allows the permanent monitoring of only one nuclear species by the nuclear magnetic resonance (NMR) method. [Copyright &y& Elsevier]

Atomic beam devices are frequently equipped with sextupole magnets to focus the beam or to act as spin filters in combination with RF-transitions for manipulating the hyperfine population within the atomic beam. A useful tool for the analysis of sextupole systems, the application of time-of-flight (TOF) measurements is presented. TOF measurements are enabled without mechanical beam chopper by utilizing adiabatic radio frequency transitions to select atoms within a certain time interval. This method is especially interesting for the use in atomic beam devices that are already equipped with RF-transitions and sextupole magnets and where space limitations or the required quality of the vacuum do not allow the installation of a mechanical chopper. The measurements presented here were performed with the atomic beam polarimeter of the HERMES polarized deuterium target and the results have been used to optimize the sextupole system of the polarimeter. [Copyright &y& Elsevier]

An atomic beam polarimeter for measurement of the hyperfine population numbers and the absolute polarization of thermal atomic hydrogen (H) and deuterium (D) beams is described. The principle of measurement and the method of calibration are given. The polarimeter measures the 4 (6) relative hyperfine population numbers of a thermal H (D) beam in the region of 1013 atoms s−1 to an absolute error of less than 0.01. The polarimeter has been in continuous operation with the internal polarized hydrogen and deuterium gas target used in the HERMES experiment at DESY since 1996. [Copyright &y& Elsevier]