Vegetation moisture content is an important early indicator of forest drought stress, disease and fire risk. Existing remote sensing techniques to measure biochemical properties of vegetation, such as Equivalent Water Thickness (EWT), are limited by an inability to differentiate canopy and understorey properties and are influenced by variations in canopy structure. By providing a range-resolved estimate of reflectance, laser scanner measurements have the potential to overcome these limitations. Dual-wavelength laser scanning can provide an active measurement of reflectance from which spectral indices can be derived that are insensitive to range, incidence angle and scattering area of the target within the laser beam, factors that make exploiting single-wavelength laser scanner intensity data difficult.This study demonstrates the potential of dual-wavelength laser scanning for measurement of leaf biochemical properties, through determining the relationship between a laser-scanner-derived spectral index, using near infrared (1063nm) and middle infrared (1545nm) wavelengths, and the EWT of individual leaves. The suitability and sensitivity of the index is tested using a leaf optical properties model (PROSPECT-5) and the method is tested experimentally under laboratory conditions using the Salford Advanced Laser Canopy Analyser. A strong relationship (R2=0.8, RMSE=0.0069gcm−2) was found between a normalised ratio of the two wavelengths and measured EWT of leaf samples. The relationship corresponds well to that predicted by modelling. However, the experimental data also revealed significant spatial variability in the index value across individual leaves, suggesting heterogeneity in moisture distribution at within-leaf scales. The study suggests significant potential for using dual-wavelength and multispectral laser scanning for measuring vegetation biochemical properties.

The Earth Observation Technology Cluster is a knowledge exchange initiative, promoting development, understanding and communication about innovative technology used in remote sensing of the terrestrial or land surface. This initiative provides an opportunity for presentation of novel developments from, and cross-fertilisation of ideas between, the many and diverse members of the terrestrial remote sensing community. The Earth Observation Technology Cluster involves a range of knowledge exchange activities, including organisation of technical events, delivery of educational materials, publication of scientific findings and development of a coherent terrestrial EO community. The initiative as a whole covers the full range of remote sensing operation, from new platform and sensor development, through image retrieval and analysis, to data applications and environmental modelling. However, certain topical and strategic themes have been selected for detailed investigation: (1) Unpiloted Aerial Vehicles, (2) Terrestrial Laser Scanning, (3) Field-Based Fourier Transform Infra-Red Spectroscopy, (4) Hypertemporal Image Analysis, and (5) Circumpolar and Cryospheric Application. This paper presents general activities and achievements of the Earth Observation Technology Cluster, and reviews state-of-the-art developments in the five specific thematic areas.

We report the first measurements of the total cross section of the reaction K{sup -}p{yields}{sigma}{sup 0}{gamma} at eight beam momenta from 514 to 750 MeV/c. The data were obtained at the Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory using the Crystal Ball detector consisting of 672 NaI crystals. All charged particles were vetoed by a barrel of plastic scintillators, resulting in a study of only the neutral decays of the {sigma}{sup 0}. The prompt photon and the photons from the decay products of {sigma}{sup 0} were detected for each reconstructed event; the neutron was also detected in a small fraction of the events.

Measured values of the differential cross sections for pion-nucleon charge exchange, pi- p --> pi0 n, are presented for pi- momenta of 103, 112, 120, 130, 139, 152, and 178 MeV/c. Complete angular distributions were obtained by using the Crystal Ball detector at the Alternating Gradient Synchrotron at Brookhaven National Laboratory. Statistical uncertainties of the differential cross sections vary from 3% to 6% in the backward angle region, and from 6% to about 20% in the forward region with the exception of the two most forward angles. The systematic uncertainties are estimated to be about 3% for all momenta.

A set of three out-of-plane magnetic spectrometers (OOPS) has recently been deployed and commissioned at the Bates Linear Accelerator. Measurements of the 2 H(~ e; e 0 p)n reaction have been performed using an 800 MeV polarized electron beam and the OOPS to detect protons in coincidence with an electron spectrometer in kinematics of either quasielastic (QE) at Q 2 =0.22 (GeV/c) 2 or non{quasielastic (dip) at Q 2 =0.15 (GeV/c) 2. Two and three OOPS were positioned symmetrically along the direction of momentum transfer in pq=(45,135) and (0,90,180) conngurations, respectively, for a given set of pq values. This allowed simultaneous measurements of the longitudinal-transverse responses, f LT and f 0 LT , and the transverse-transverse response f TT at various central missing momenta ranging from 145 to 265 MeV/c. Here, preliminary results are presented and compared with vigorous model calculations. The data reveal strong eeects of relativity and nal-state interactions, as well as the two-body currents, which include the meson-exchange and iso-bar currents, in the deuteron electrodisintegration. An outlook of future OOPS programs is also discussed.

The reaction K(-)p ->Sigma(0)pi(0)-> neutrals was studied with the Crystal Ball detector at the BNL Alternating Gradient Synchrotron for beam momenta between 514 and 750 MeV/c. The photons from Sigma(0) and pi(0) decays were detected, as well as the neutron in a small fraction of the events. The differential cross section and the Sigma(0) polarization are reported at eight momenta and nearly the full angular range. Total cross sections are derived from Legendre polynomial fits to the data. The measurements presented are of considerably higher precision than previous results.

New results on the rare, doubly radiative decay η →π 0 γγ have been obtained from a revised analysis of the Crystal Ball experiment performed at the AGS. The analysis yields the first information on the dependence of the decay width, F(η →π 0 γγ), on the two-photon invariant mass squared, m 2 (γγ). A re-evaluation of the branching ratio is also made, BR(η→ π 0 γγ) = (2.21 ± 0.24 stat ± 0.47 syst ) x 10 -4 ; it implies that the decay width is r(η →r 0 γγ) = 0.285 ± 0.031 stat ± 0.061 syst eV. These results are close to predictions based on chiral perturbation theory with vector-meson dominance.

We report a new measurement of the differential cross section for pi(-)p ->pi(0)n from p(pi)=649 to 752 MeV/c, which is around the opening of the eta channel (685 MeV/c). Our data support the main features of the pi(-)p charge-exchange differential cross sections generated by the SAID pi N partial-wave analysis. The opening of the eta channel has a clear effect on the shape of the excitation function for d sigma(pi(-)p ->pi(0)n), which is most noticeable in the backward direction.

The branching ratio (BR) for the rare decay eta ->pi(0)gamma gamma was measured with the Crystal Ball multiphoton spectrometer. The result, BR(eta ->pi(0)gamma gamma)=(3.5 +/- 0.7(stat)+/- 0.6(syst))x10(-4), is in agreement with calculations of chiral perturbation theory to third order. We have used a sample of 28 million eta mesons produced at the BNL Alternating Gradient Synchrotron using the pi(-)p ->eta n reaction close to threshold. We detail the intricate extraction of the signal, which has about 1.6 thousand eta ->pi(0)gamma gamma events, from the overwhelming background of eta -> 3 pi(0) decays and from the pi(-)p ->pi(0)pi(0)n reaction.

The differential cross section for \ensuremath{\eta} production in reaction ${\ensuremath{\pi}}^{\ensuremath{-}}p\ensuremath{\rightarrow}\ensuremath{\eta}n$ has been measured over the full angular range at seven incident ${\ensuremath{\pi}}^{\ensuremath{-}}$ beam momenta from threshold to ${p}_{{\ensuremath{\pi}}^{\ensuremath{-}}}=747$ MeV/c using the Crystal Ball multiphoton spectrometer. The angular distributions are S wave dominated. At 10 MeV/c above threshold, a small D-wave contribution appears that interferes with the main S wave. The total \ensuremath{\eta} production cross section ${\ensuremath{\sigma}}^{\mathrm{tot}}$ is obtained by integration of $d\ensuremath{\sigma}/d\ensuremath{\Omega}$. Starting at threshold, ${\ensuremath{\sigma}}^{\mathrm{tot}}$ rises rapidly, as expected for S-wave-dominated production. The features of the ${\ensuremath{\pi}}^{\ensuremath{-}}p\ensuremath{\rightarrow}\ensuremath{\eta}n$ cross section are strikingly similar to those of the SU(3) flavor-related process ${K}^{\ensuremath{-}}p\ensuremath{\rightarrow}\ensuremath{\eta}\ensuremath{\Lambda}$. Comparison of the ${\ensuremath{\pi}}^{\ensuremath{-}}p\ensuremath{\rightarrow}\ensuremath{\eta}n$ reaction is made with \ensuremath{\eta} photoproduction.

The differential cross section for eta production in reaction pi(-)p ->eta n has been measured over the full angular range at seven incident pi(-) beam momenta from threshold to p(pi)(-)=747 MeV/c using the Crystal Ball multiphoton spectrometer. The angular distributions are S wave dominated. At 10 MeV/c above threshold, a small D-wave contribution appears that interferes with the main S wave. The total eta production cross section sigma(tot) is obtained by integration of d sigma/d Omega. Starting at threshold, sigma(tot) rises rapidly, as expected for S-wave-dominated production. The features of the pi(-)p ->eta n cross section are strikingly similar to those of the SU(3) flavor-related process K(-)p ->eta Lambda. Comparison of the pi(-)p ->eta n reaction is made with eta photoproduction.