Spin-dependent electron-proton scattering in the Delta-excitation region

We report on measurements of the cross section and provide first data on spin correlation parameters A(TT') and A(TL') in inclusive scattering of longitudinally polarized electrons from nuclear-polarized hydrogen. Polarized electrons were injected into an electron storage ring operated at a beam energy of 720 MeV. Polarized hydrogen was produced by an atomic beam source and injected into an open-ended cylindrical cell, located in the electron storage ring. The four-momentum transfer squared ranged from Q2 = 0.2 GeV(2)/c(2) at the elastic scattering peak to Q2 = 0.11 GeV(2)/c(2) at the Delta(1232) resonance. The data provide a stringent test of pion electroproduction models.     

Measurements of the proton elastic-form-factor ratio mu pG p E/G p M at low momentum transfer

High-precision measurements of the proton elastic form-factor ratio, mu pG p E/G p M, have been made at four-momentum transfer, Q2, values between 0.2 and 0.5 GeV2. The new data, while consistent with previous results, clearly show a ratio less than unity and significant differences from the central values of several recent phenomenological fits. By combining the new form-factor ratio data with an existing cross-section measurement, one finds that in this Q2 range the deviation from unity is primarily due to G p E being smaller than expected.     

Spin-momentum correlations in quasielastic electron scattering from deuterium

The spin-momentum correlation parameter A(V)(ed) was measured for the 2H-->(e-->,e'p)n reaction for missing momenta up to 350 MeV/c at Q2 = 0.21 (GeV/c)(2) for quasielastic scattering of polarized electrons from vector-polarized deuterium. The data give detailed information about the deuteron spin structure and are in good agreement with the results of microscopic calculations based on realistic nucleon-nucleon potentials and including various spin-dependent reaction mechanism effects. The experiment reveals in a most direct manner the effects of the D state in the deuteron ground-state wave function and shows the importance of isobar configurations for this reaction.     

Radiative charged pion photoproduction and pion polarizabilities: An analysis within heavy baryon chiral perturbation theory

We analyze the amplitude for radiative charged pion photoproduction within the framework of heavy baryon chiral perturbation theory and discuss the best experimental setup for the extraction of the pion polarizabilities from the differential cross section. Correspondence: C.-W. Kao, Department of Physics, Chung Yuan Christian University, Chung-Li 320, Taiwan     

Proton spin structure in the resonance region

We have examined the spin structure of the proton in the region of the nucleon resonances (1.085 GeV相似文献   

Coherent population transfer in an atom by multiphoton adiabatic rapid passage

Coherent population transfer in an atom using a sequence of adiabatic rapid passages through single-photon resonances is well-known, but it requires that the frequency sweep match the changing frequencies of the atomic transitions. The same population transfer can be effected via a single multiphoton adiabatic rapid passage, which requires only a small frequency sweep, if it is possible to select the desired multiphoton transition from the many possible transitions. Here we report the observation of population transfer between Rydberg states by high order multiphoton adiabatic rapid passage.     

Photochemical Internalization of Bleomycin is Superior to Photodynamic Therapy Due to the Therapeutic Effect in the Tumor Periphery

Photochemical internalization (PCI) is under development for clinical use in treatment of soft tissue sarcomas and other solid tumors. PCI may release endocytosed bleomycin (BLM) into the cytosol by photochemical rupture of the endocytic vesicles. In this study, the human fibrosarcoma xenograft HT1080 was transplanted into the leg muscle of athymic mice. The photosensitizer disulfonated aluminum phthalocyanine (AlPcS_2a) and BLM were systemically administrated 48 h and 30 min, respectively, prior to light exposure at 670 nm (30 J cm⁻²). The purposes of this study were to evaluate the treatment response to AlPcS_2a-photodynamic therapy (PDT) and AlPcS_2a-PDT in combination with BLM ( i.e. PCI of BLM) in an orthotopic, invasive and clinically relevant tumor model and to explore the underlying response mechanisms caused by PDT and PCI of BLM. The treatment response was evaluated by measuring tumor growth, contrast-enhanced magnetic resonance imaging (CE-MRI), histology and fluorescence microscopy. The results show that PCI of BLM is superior to PDT in inducing tumor growth retardation and acts synergistically as compared to the individual treatment modalities. The CE-MRI analyses 2 h after AlPcS_2a-PDT and PCI of BLM identified a treatment-induced nonperfused central zone of the tumor and a well-perfused peripheral zone. While there were no differences in the vascular response between PDT and PCI, the histological analyses showed that PDT caused necrosis in the tumor center and viable tumor cells were found in the tumor periphery. PCI caused larger necrotic areas and the regrowth in the peripheral zone was almost completely inhibited after PCI. The results indicate that PDT is less efficient in the tumor periphery than in the tumor center and that the treatment effect of PCI is superior to PDT in the tumor periphery.