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The observational climate record is a cornerstone of our scientific understanding of climate changes and their potential causes. Existing observing networks have been designed largely in support of operational weather forecasting and continue to be run in this mode. Coverage and timeliness are often higher priorities than absolute traceability and accuracy. Changes in instrumentation used in the observing system, as well as in operating procedures, are frequent, rarely adequately documented and their impacts poorly quantified. For monitoring changes in upper-air climate, which is achieved through in-situ soundings and more recently satellites and ground-based remote sensing, the net result has been trend uncertainties as large as, or larger than, the expected emergent signals of climate change. This is more than simply academic with the tropospheric temperature trends issue having been the subject of intense debate, two international assessment reports and several US congressional hearings. For more than a decade the international climate science community has been calling for the instigation of a network of reference quality measurements to reduce uncertainty in our climate monitoring capabilities. This paper provides a brief history of GRUAN developments to date and outlines future plans. Such reference networks can only be achieved and maintained with strong continuing input from the global metrological community. [ABSTRACT FROM AUTHOR]

We describe the implementation of evaporative cooling of charged particles in the ALPHA apparatus. Forced evaporation has been applied to cold samples of antiprotons held in Malmberg-Penning traps. Temperatures on the order of 10 K were obtained, while retaining a significant fraction of the initial number of particles. We have developed a model for the evaporation process based on simple rate equations and applied it succesfully to the experimental data. We have also observed radial re-distribution of the clouds following evaporation, explained by simple conservation laws. We discuss the relevance of this technique for the recent demonstration of magnetic trapping of antihydrogen. [ABSTRACT FROM AUTHOR]

Long term magnetic confinement of antihydrogen atoms has recently been demonstrated by the ALPHA collaboration at CERN, opening the door to a range of experimental possibilities. Of particular interest is a measurement of the antihydrogen spectrum. A precise comparison of the spectrum of antihydrogen with that of hydrogen would be an excellent test of CPT symmetry. One prime candidate for precision CPT tests is the ground-state hyperfine transition; measured in hydrogen to a precision of nearly one part in 1012. Effective execution of such an experiment with trapped antihydrogen requires precise knowledge of the magnetic environment. Here we present a solution that uses an electron plasma confined in the antihydrogen trapping region. The cyclotron resonance of the electron plasma is probed with microwaves at the cyclotron frequency and the subsequent heating of the electron plasma is measured through the plasma quadrupole mode frequency. Using this method, the minimum magnetic field of the neutral trap can be determined to within 4 parts in 104. This technique was used extensively in the recent demonstration of resonant interaction with the hyperfine levels of trapped antihydrogen atoms. [ABSTRACT FROM AUTHOR]

Over the last decades it has become routine to form beams of positrons and antiprotons and to use them to produce trapped samples of both species for a variety of purposes. Positrons can be captured efficiently, for instance using a buffer-gas system, and in such quantities to form dense, single component plasmas useful for antihydrogen formation. The latter is possible using developments of techniques for dynamically capturing and then cooling antiprotons ejected from the Antiproton Decelerator at CERN. The antiprotons can then be manipulated by cloud compression and evaporative cooling to form tailored plasmas. We will review recent advances that have allowed antihydrogen atoms to be confined for the first time in a shallow magnetic minimum neutral atom trap superimposed upon the region in which the antiparticles are held and mixed. A new mixing technique has been developed to help achieve this using autoresonant excitation of the centreofmass longitudinal motion of an antiproton cloud. This allows efficient antihydrogen formation without imparting excess energy to the antiprotons and helps enhance the probability of trapping the anti-atom. [ABSTRACT FROM AUTHOR]

The compression-mode isoscalar giant monopole resonance (ISGMR) has been studied in the Sn, Cd and Pb isotopes using inelastic scattering of 400 MeV α-particles at extreme forward angles, including 0°. We have obtained completely 'background-free' inelastic-scattering spectra for the Sn, Cd, and Pb isotopes for a wide angular and excitation-energy range. The various giant resonances excited with different transferred angular momenta were extracted by a multipole-decomposition analysis (MDA). It was found that the centroid energies of the ISGMR in Sn isotopes are significantly lower than the theoretical predictions. The Kτ in the empirical expression for the nuclear incompressibility has been determined to be Kτ = -550±100 MeV for the Sn isotopes. The extracted value for the Cd isotopes is Kτ = -480±100 MeV. These numbers are consistent with values of Kτ = -370±120 MeV obtained from an analysis of the isotopic transport ratios in medium-energy heavy-ion reactions, Kτ = -500-100+120 MeV obtained from constraints placed by neutron-skin data from anti-protonic atoms across the mass table, and Kτ = -500±50 MeV obtained from theoretical calculations using different Skyrme interactions and relativistic mean field (RMF) Lagrangians. Stringent constraints on interactions employed in nuclear structure calculations are obtained on the basis of the experimentally determined values for K∞ and Kτ. These parameters constrain as well the equation of state (EOS) of nuclear matter. However, a significant discrepancy still remains. The ISGMR positions in Sn and Cd isotopes are systematically lower than the predictions obtained on basis of determined from the ISGMR in 208Pb. This raises the question 'Why are Sn and Cd nuclei so soft?'. For a clue to solve the problem, we discuss the preliminary results on the exact positions of the ISGMR in 204,206,208Pb. [ABSTRACT FROM AUTHOR]

The alpha inelastic scattering from 24Mg was measured to obtain the isoscalar natural-parity excitation strengths and to search for the α-condensed states. The multipole decomposition analysis for the measured cross sections was performed. The strength distributions for the ΔL = 0-3 were successfully obtained and the possible candidates for the α-condensed states around the 16O core were found. [ABSTRACT FROM AUTHOR]

The compressional-mode giant resonances, the isoscalar giant monopole resonance (GMR) and the isoscalar giant dipole resonance (ISGDR), in various isotopes have been investigated using inelastic scattering of 400-MeV α-particles at extremely forward angles, including 0°. Recently, the centroid energies of the giant monopole resonance (GMR) in the Sn isotope region are found to be significantly lower than the theoretical predictions. In addition, based on the GMR results, the asymmetry-term in the nuclear incompressibility has been determined as Kτ = -550±100 MeV. Constraints on interactions employed in nuclear structure calculations are discussed on the basis of the experimentally values for K∞ and Kτ. The combination of these two values gives stringent constraints on the interactions used for nuclear structure calculations and for formations of equation of state (EOS) of nuclear matter. A short review of the current status of the experimental studies on the compressional-mode giant resonances is given, and a possible new experiment for astrophysics and physics with exotic nuclei is suggested. [ABSTRACT FROM AUTHOR]

We studied transition strengths to isovector dipole resonances (GDR-1[overbar], SDR-1[overbar], and SDR-2[overbar]) in 4He by using the 4He(7Li,7Beγ) reaction at 455 MeV and by comparing with shell-model calculations, in order to estimate cross sections of 4He for reactions induced by neutrinos emitting from a thermalized neutrino-sphere in the type-II supernova. Excitation of the SDR was dominant in the neutrino-heating of 4He. The 4He-excitation via neutral-current reactions of νμ,τ and νμ,τ was found to be one order of magnitude stronger than that via charged-current reactions of νe and νe. The total energy-weighted cross section <ωσ>N for neutrino-induced neutral-current reactions on 4He was found to amount to about 1.0×10-40 MeV·cm2 which is comparable to those used in the previous simulations. The neutrino-heating effect of 4He is small in the type-II supernova explosion. [ABSTRACT FROM AUTHOR]

A polarized 3He ion source has been developed at RCNP for intermediate and high energy spin physics. Though we started with an OPPIS (Optical Pumping Polarized Ion Source), it could not provide highly polarized 3He beam because of fundamental difficulties. Subsequently to this unhappy result, we examined novel types of the polarized 3He ion source, i.e., EPPIS (Electron Pumping Polarized Ion Source), and ECRPIS (ECR Polarized Ion Source) experimentally or theoretically, respectively. However, attainable 3He polarization degrees and beam intensities were still insufficient for practical use. A few years later, we proposed a new idea for the polarized 3He ion source, SEPIS (Spin Exchange Polarized Ion Source) which is based on enhanced spin-exchange cross sections at low incident energies for 3He++Rb, and its feasibility was experimentally examined. Recently, we started a project on polarized 3He gas generated by the brute force method with low temperature (∼4 mK) and strong magnetic field (∼17 T), and rapid melting of highly polarized solid 3He followed by gasification. When this project will be successful, highly polarized 3He gas will hopefully be used for a new type of the polarized 3He ion source. [ABSTRACT FROM AUTHOR]

We discuss aspects of antihydrogen studies, that relate to particle physics ideas and techniques, within the context of the ALPHA experiment at CERN's Antiproton Decelerator facility. We review the fundamental physics motivations for antihydrogen studies, and their potential physics reach. We argue that initial spectroscopy measurements, once antihydrogen is trapped, could provide competitive tests of CPT, possibly probing physics at the Planck Scale. We discuss some of the particle detection techniques used in ALPHA. Preliminary results from commissioning studies of a partial system of the ALPHA Si vertex detector are presented, the results of which highlight the power of annihilation vertex detection capability in antihydrogen studies. [ABSTRACT FROM AUTHOR]

The ALPHA apparatus is designed to produce and trap antihydrogen atoms. The device comprises a multifunction Penning trap and a superconducting, neutral atom trap having a minimum-B configuration. The atom trap features an octupole magnet for transverse confinement and solenoidal mirror coils for longitudinal confinement. The magnetic trap employs a fast shutdown system to maximize the probability of detecting the annihilation of released antihydrogen. In this article we describe the first attempts to observe antihydrogen trapping. [ABSTRACT FROM AUTHOR]

Control of the radial profile of trapped antiproton clouds is critical to trapping antihydrogen. We report detailed measurements of the radial manipulation of antiproton clouds, including areal density compressions by factors as large as ten, achieved by manipulating spatially overlapped electron plasmas. We show detailed measurements of the near-axis antiproton radial profile, and its relation to that of the electron plasma. We also measure the outer radial profile by ejecting antiprotons to the trap wall using an octupole magnet. [ABSTRACT FROM AUTHOR]

We investigated charged-particle decay from the high-lying dipole resonances at Ex=24 MeV in 6He and at 18 MeV in 7He via the 6,7Li(7Li,7Be x) reactions at 455 MeV and at 0°. d- and t-decay, and t-decay was observed as the dominant decay modes for these resonances in 6He and 7He, respectively. The yield ratios observed for charged particle decay were qualitatively consistent with those expected from the assumption that the resonances are the analogs of the dipole resonances in the α cluster in 6Li and 7Li, but could not be explained by simple phase space calculations. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

We investigated the analogs of the giant dipole resonance (GDR) and spin-dipole resonance (SDR) of 4He by using the 4He(7Li,7Be) reaction at an incident energy of 455 MeV and at forward scattering angles. The ΔS=0 and ΔS=1 spectra for 4He were obtained by measuring the 0.43-MeV 7Be γ-ray in coincidence with the scattered 7Be. From the ΔS=0 and ΔS=1 spectra thus obtained, the strength distributions of the GDR and SDR in 4He can be derived and the results are compared with the previous data. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

The asymmetries in the nuclear resonance fluorescence (NRF) processes with a circular polarized photon beam are shown to be a good tool for studying the parity non-conservation (PNC) in nuclei. The PNC asymmetry measurements both in exciting the parity doublet states and in exciting the discrete states near the ground states with parity mixing are discussed. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

The (7Li,7Be) charge-exchange spin-flip reaction was for the first time used to deduce the distribution of the B(M1) reduced matrix elements for the photodisintegration of deuteron from the analogous B(GT) distribution. The obtained distribution is in agreement with recent photodisintegration measurements and effective-field calculations. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

The isovector giant dipole resonance (GDR) of the α-clusters in 6Li and 7Li, and the GDR in 4He were investigated by using the 6,7Li(p,p′) and 4He(p,p′) reactions, respectively, at an incident energy of 300 MeV. The cross sections for the excitation of the GDR in the α clusters in 6,7Li normalized with the spectroscopic factors of the α-particle for 6,7Li agreed to the GDR cross section in 4He. The excitation energies and widths for the GDR in α clusters were larger than those for the GDR in 4He by 2–4 MeV and 0.5–4 MeV, respectively. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

The ATHENA experiment at CERN produced for the first time in 2002 cold antihydrogen atoms by mixing of antiprotons and a positron plasma. The more relevant results obtained in the last three years are presented and discussed in the light of the antihydrogen formation processes. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

The ALPHA experiment aims to trap antihydrogen as the next crucial step towards a precise CPT test, by a spectroscopic comparison of antihydrogen with hydrogen. The experiment will retain the salient techniques developed by the ATHENA collaboration during the previous phase of antihydrogen experiments at the antiproton decelerator (AD) at CERN. The collaboration has identified the key problems in adding a neutral antiatom trap to the previously developed experimental configuration. The solutions identified by ALPHA are described in this paper. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

Antihydrogen atoms may become the easiest and most precise way to probe deeply into tests of violation of the CPT (charge conjugation, parity, time reversal) symmetry and the Weak Equivalence Principle (WEP). We review the first production of cold antihydrogen atoms within the ATHENA/AD-1 experiment at CERN, its motivations and studies henceforth. The ATHENA success was followed almost immediately by the ATRAP group. From the initial claim of production of tens of thousand of these exotic species — by the mixing of cold and trapped positrons and antiprotons — we have evolved to better understand and control the system. The joint production for 2002 and 2003 has been re-evaluated to about one million antiatoms. We have performed cooling efficiency studies of antiprotons within the positron cloud; developed ways to excite and heat the positron cloud, and probe its number, density and temperature in situ; developed antiproton and antihydrogen imaging tomography. We have also been able to gather information on the velocity of the formed antiatoms. A large uncertainty and lack of control remains over the formation process — as revealed by its measured temperature dependence — and the quantum number distribution of the population. We discuss various aspects of our findings below as well as future prospects for physics tests with antihydrogen. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

We present two kinds of experimental results. One is a continuous variable dense coding experiment, and the other is a photon number detector with high linearity response, the so called charge integration photon detector (CIPD). They can be combined together to be a potential tool for implementing the cubic phase gate which is an important gate element to synthesize the measurement induced nonlinearity for photonic quantum information processing. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Antihydrogen, the antimatter counterpart of the hydrogen atom, can be formed by mixing cold samples of antiprotons and positrons. In 2002 the ATHENA collaboration succeeded in the first production of cold antihydrogen. By observing and imaging the annihilation products of the neutral, non-confined, antihydrogen atoms annihilating on the walls of the trap we can observe the production in quasi-real-time and study the dynamics of the formation mechanism. The formation mechanism strongly influences the final state of the formed antihydrogen atoms, important for future spectroscopic comparison with hydrogen. This paper briefly summarizes the current understanding of the antihydrogen formation in ATHENA. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Tri-nucleon molecular structures in 6He and 6Be were investigated by using the 6Li(7Li,7Be)6He reaction at 455 MeV and 6Li(3He,t)6Be reaction at 450 MeV, respectively. Binary decay into t+t from a broad state at Ex = 18.0 ± 1.0 MeV in 6He and into 3He+3He from one at Ex = 18.0 ± 1.2 MeV in 6Be, were observed by measuring tri-nucleon cluster-decays in coincidence with reaction-particles. The branching ratios for binary decay were estimated to be about 0.7 for both 6He and 6Be. From the angular correlations of decay particles, these states are assigned to be P states. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

The isovector giant dipole resonance (GDR) of an α-cluster in 6Li and 7Li, and their analogs in 6,7He and 6,7Be were searched for by using the 6,7Li(p,p′), 6,7Li(3He,t) and 6,7Li(7Li,7Be) reactions at the incident energies of 300, 450 and 455 MeV, respectively. New resonances were found for the first time at Ex=27.0±1.5 MeV in 6Li and at Ex=29.0±1.5 MeV in 7Li, both with widths (FWHM) of 12±2 MeV. In 6He, 6Be, 7He and 7Be resonances with widths of 12±2 MeV were observed via the charge exchange reactions at Ex=24.0±1.5, 23.5±1.5, 18.0±1.5, and 28.0±1.5 MeV, respectively. All of these resonances were assigned to be dipole resonances based on the measured angular distributions of differential cross sections. The resonance shapes were reproduced well with the resonance shape of the GDR of 4He reported in the (γ,n) reaction. The averaged ratios of the cross sections for these resonances in A=6 to those in A=7 for each isotope were estimated to be nealy unity, 1.2±0.3. The averaged value of the respective cross section ratios of these resonances to the GDR in their respective target nuclei was 0.44±0.08, which was consistent with the ratios of the cross sections of the GDR in 4He to those of the GDR in 6,7Li reported in the photo-nuclear reactions. The excitation energies of these dipole resonances in A=6 and 7 nuclei relative to the separation energies of an α-particle in 6Li and 7Li, respectively, agreed well with the excitation energy of the GDR in 4He (≈26 MeV). We conclude that the resonances observed in 6,7Li are the GDR of the α-cluster and the resonances in 6,7He and 6,7Be are their analogs. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Observations of anti-hydrogen in small quantities have been reported at CERN and at FermiLab, but these experiments were not suited to spectroscopy experiments. In 2002 the ATHENA collaboration reported the production and detection of very low energy anti-hydrogen atoms produced in cryogenic environment. This is the first major step in the study of antiatom’s internal structure and it can lead to a high precision test of the CPT fundamental symmetry. The method of production and detection of cold anti-hydrogen will be introduced. The absolute rate of anti-hydrogen production and the signal to background ratio in the ATHENA experiment will be discussed. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Cross sections and polarization transfer observables in the 16O(p,p′) reactions at 392 MeV were measured at forward angles including 0°. The non-spin-flip (ΔS = 0) and spin-flip (ΔS = 1) strengths in transitions to several discrete states and broad resonances in 16O were extracted using a model-independent method. The giant resonances in the energy region of E x = 19–27 MeV were found to be predominantly excited by ΔL = 1 transitions. The strength distribution of spin-dipole transitions with ΔS = 1 and ΔL = 1 were deduced. The obtained distribution was compared with a recent shell model calculation. Experimental results are reasonably explained by distorted-wave impulse-approximation calculations with the shell model wave functions. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

A new method for studying the neutron-skin thickness has been critically tested. The method is based on the excitation of the giant (spin-)dipole resonances in charge-exchange reactions. For a precise experimental test the ([sup 3]He,t) reaction on even-Sb isotopes has been used. The results obtained are in good agreement with the previous experimental and theoretical ones. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The isoscalar giant dipole resonance (ISGDR) has been investigated in [sup 208]Pb using inelastic scattering of 400 MeV α particles at extremely forward angles, including 0°. Using the superior capabilities of the Grand Raiden spectrometer, it has been possible to obtain inelastic spectra devoid of any “instrumental” background. The ISGDR strength distribution has been extracted from a multipole-decomposition of the observed spectra. The implications of these results on the experimental value of nuclear incompressibility are discussed. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The Laser-Electron-Photon facility at SPring-8 (LEPS) is now taking data for all hadronic reactions at compton-backscattered photon energies between 1.5 GeV and 2.4 GeV. A linearly polarized photon beam is incident on a liquid hydrogen target or nuclear targets. A large dipole spectrometer analyzes charged particles produced at forward angles. First results from SPring8/LEPS will be presented with special emphasis on the study of photoproduction of φ mesons near threshold. Some prospects for the near future will also be presented and discussed in close connection with photoproduction of hyperons. [ABSTRACT FROM AUTHOR]

Polarization transfer (PT) coefficients in the [sup 12]C, [sup 28]Si(p,p') reactions at a scattering angle of 0° are measured at E[sub p] = 392 MeV. The strength of the isoscalar central spin-dependent part (V[sub σ]) of the effective nucleon-nucleon interaction is studied by using the sensitivity of the PT coefficients for the excitation of the 1[sup +], T=0 state in [sup 12]C to the V[sub σ] strength. It is found that distorted wave impulse approximation (DWIA) calculations employing the Francy and Love effective interaction well reproduce the measured PT coefficients. [ABSTRACT FROM AUTHOR]

Complete sets of observables in proton inelastic scattering from [sup 16]O have been measured at forward angles including 0°. Obtained spectra were decomposed into spin-flip and non spin-flip spectra by polarization transfer coefficients and spindipole strength spliting into several peaks was identified in the giant resonance region of E[sub x] = 19 ∼ 27 MeV in [sup 16]O. [ABSTRACT FROM AUTHOR]

We have constructed an experimental ensemble to measure polarization transfer observables in proton inelastic scattering at zero degrees. Excited states can simultaneously be measured for the excitation energy from 5 MeV to 35 MeV at E[sub p]=400 MeV. A fast data acquisition system has been developed to endure the large background event rate originated by the primary beam itself. We have found the effective analyzing power of the focal plane polarimeter slightly depends on the treatment of two-ray events. [ABSTRACT FROM AUTHOR]