The 51V(p,n)51Cr reaction at Ep = 160 MeV

The ⁵¹V(p, n)⁵¹Cr reaction has been studied at E_p = 160 MeV using the Indiana University beam-swinger facility. Data have been obtained at several angles up to θ_L = 20°. The 0° spectrum is used to obtain a ΔL = 0 response function from which Gamow-Teller strength is derived. A shell-model calculation of the GT strength distribution is presented and compared with the experimental results. The M1 strength is also calculated and compared with available results from (e, e') and (p, p') experiments. A comparison is made with other N = 28 nuclei. Effects of a truncated shell-model space are presented.     

Indolopyridines with a hetero atom at a position of fusion. 7. Electrophilic substitution in 5,6-dihydroindolo-[2,1-a]isoquinoline

Halogenation, acylation, azo coupling, and alkylaminomethylation of 5,6-dihydroindoto[2,I-alisoguinoline were carried out at the C₍₁₁₎ position (pyrrole fragment). In dibromination, the second bromine atom was introduced into the C₍₉₎ position (indole part of the molecule).Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 217–220, February, 1994. Original article submitted November 19, 1993.     

Investigation of the conjectured nucleon deformation at low momentum transfer

We report new precise H(e,e(')p)pi(0) measurements at the Delta(1232) resonance at Q(2)=0.127 (GeV/c)(2) obtained at the MIT-Bates out-of-plane scattering facility which are particularly sensitive to the transverse electric amplitude (E2) of the gamma(*)N-->Delta transition. The new data have been analyzed together with those of earlier measurements to yield precise quadrupole to dipole amplitude ratios: Re(E(3/2)(1+)/M(3/2)(1+))=(-2.3+/-0.3(stat+syst)+/-0.6(model))% and Re(S(3/2)(1+)/M(3/2)(1+))=(-6.1+/-0.2(stat+syst)+/-0.5(model))% for M(3/2)(1+)=(41.4+/-0.3(stat+syst)+/-0.4(model))(10(-3)/m(pi(+))). The derived amplitudes give credence to the conjecture of deformation in hadrons favoring, at low Q2, the dominance of mesonic effects.     

An alternative approach to combination vaccines: intradermal administration of isolated components for control of anthrax,botulism, plague and staphylococcal toxic shock

Background  

Combination vaccines reduce the total number of injections required for each component administered separately and generally provide the same level of disease protection. Yet, physical, chemical, and biological interactions between vaccine components are often detrimental to vaccine safety or efficacy.     

Status of the BLAST project

The Bates Large Acceptance Spectrometer Toroid (BLAST) is a detector designed to study the spin-dependent electromagnetic response of few-body nuclei at momentum transfers up to 1 (GeV/c)² at the MIT/Bates Linear Accelerator Center's South Hall Ring (SHR). The BLAST detector consists of an eight-sector copper coil array producing a toroidal magnetic field, instrumented with two opposing wedge-shaped sectors of wire chambers, scintillation detectors, Cerenkov counters, neutron detectors, a lead-glass fo ward calorimeter, and recoil detectors. Presently, BLAST is under construction and it is on schedule to be done in summer 2001. A status of the project is presented as well as highlights of the scientific program.     

Search for quadrupole strength in the electroexcitation of the delta+(1232)

High-precision 1H(e,e'p)pi(0) measurements at Q2 = 0.126 (GeV/c)2 are reported, which allow the determination of quadrupole amplitudes in the gamma*N-->Delta transition; they simultaneously test the reliability of electroproduction models. The derived quadrupole-to-dipole ( I = 3/2) amplitude ratios, R(SM) = (-6.5+/-0.2(stat+sys)+/-2.5(mod))% and R(EM) = (-2.1+/-0.2(stat+sys)+/-2.0(mod))%, are dominated by model error. Previous R(SM) and R(EM) results should be reconsidered after the model uncertainties associated with the method of their extraction are taken into account.     

Nucleon form factors and the BLAST experiment

Measurements of the electric and magnetic form factors of the nucleon present a sensitive test of nucleon models and QCD-inspired theories. A precise knowledge of the neutron form factors at low Q² is also essential to reduce the systematic errors of parity violation experiments. At the MIT-Bates Linear Accelerator Center, the nucleon form factors have been measured by means of scattering of polarized electrons from vector-polarized hydrogen and deuterium. The experiment used the longitudinally polarized stored electron beam of the MIT-Bates South Hall Ring along with an isotopically pure, highly vector-polarized internal atomic hydrogen and deuterium target provided by an atomic beam source. The measurements have been carried out with the symmetric Bates Large Acceptance Spectrometer Toroid (BLAST) with enhanced neutron detection capability.     

-Measurement of the proton's electric to magnetic form factor ratio from 1H(over -->)(e(over -->),e'p)

We report the first precision measurement of the proton electric to magnetic form factor ratio from spin-dependent elastic scattering of longitudinally polarized electrons from a polarized hydrogen internal gas target. The measurement was performed at the MIT-Bates South Hall Ring over a range of four-momentum transfer squared Q2 from 0.15 to 0.65 (GeV/c)(2). Significantly improved results on the proton electric and magnetic form factors are obtained in combination with existing cross-section data on elastic electron-proton scattering in the same Q2 region.     

Ultraclean derivatized monodisperse gold nanoparticles through laser drop ablation customization of polymorph gold nanostructures

We report a novel nanosecond laser ablation synthesis for spherical gold nanoparticles as small as 4 nm in only 5 s (532 nm, 0.66 J/cm(2)), where the desired protecting agent can be selected in a protocol that avoids repeated sample irradiation and undesired exposure of the capping agent during ablation. This method takes advantage of the recently developed synthesis of clean unprotected polymorph and polydisperse gold nanostructures using H(2)O(2) as a reducing agent. The laser drop technique provides a unique tool for delivering controlled laser doses to small drops that undergo assisted fall into a solution or suspension of the desired capping agent, yielding monodisperse custom-derivatized composite materials using a simple technique.