Working group report: Collider Physics

This is summary of the activities of the working group on collider physics in the IXth Workshop on High Energy Physics Phenomenology (WHEPP-9) held at the Institute of Physics, Bhubaneswar, India in January 2006. Some of the work subsequently done on these problems by the subgroups formed during the workshop is included in this report.     

On the singularity of Green's tensor for a perfectly conducting semi-infinite cone

This paper is intended to clarify a misunderstanding concerningthe source singularity of the electric Green's tensor for aperfectly conducting semi-infinite cone of circular cross-section.Tai's series expansion of the Green's tensor is known to lacka singular term at the source region. Jones has reconstructedthe solution to this problem and has pointed out the differencebetween his result and that of Tai. The aim of our paper isto demonstrate that, although Jones's closed-form solution iscorrect, there is a mistake in his comparison with Tai's seriessolution. We conclude that one of the two additional singularterms that Jones claims as missing from Tai's formula must beomitted. Besides, we compare Jones's closed-form solution withSmyshlyaev's solution to the very same problem. We concludethat the magnetic field expressions given by Jones and Smyshlyaevcoincide, but a singular term is missing from Smyshlyaev's expressionfor the electric field.     

Vibrational spectra of silsesquioxanes impregnated with the metallocene catalyst bis(eta(5)-cyclopentadienyl)zirconium(IV) dichloride

FT-IR photoacoustic and Raman spectroscopy have been used to study the interactions between the metallocene catalyst, Cp(2)ZrCl(2) (Cp=eta(5)-C(5)H(5)), and two polyhedral oligomeric silsesquioxanes (POSS) supports. The first silsesquioxane support, POSS(h), contains (beta-hydroxyl)-tertiary amine groups, while in the second one, POSS(u), these -OH groups have been converted into N-(p-toluyl) urethane groups. The vibrational spectra of the Cp(2)ZrCl(2):POSS(h) and Cp(2)ZrCl(2):POSS(u) samples show that the Cp(2)ZrCl(2) catalyst reacts with the C-OH groups of POSS(h) and also interacts with N-H and >CO groups of POSS(u). Furthermore, Cp(2)ZrCl(2) can react with the Si-OH groups of the POSS supports and also interact with the O atoms that are bonded to the benzene rings and the N atoms of the tertiary amines in both silsesquioxanes. As a result of the interactions between Cp(2)ZrCl(2) and the POSS supports, acidic species are generated. The Cp(2)ZrCl(2):POSS(h) mass ratio seems to be an important parameter in the formation of Zr-O bonds and the acidic species.     

Scattering by small defects in the neighbourhood of a fluid-solid interface

The scattering of incident plane elastic waves by a varietyof different defects that lie upon a fluid-solid interface isconsidered here using matched asymptotic expansions. The expansionscheme is developed in terms of a parameter , the ratio of typicaldefect length scale to a typical wavelength of the incidentfield, taken to be small. Three different canonical situations occur and these are illustratedvia three specific examples treated here: a rigid strut, anedge crack, and a rigid strip. In each case the leading-ordermatching is performed to identify the leading-order contributionof the defect to the acoustic field in the far field. In particular,each defect is identified with a source of dipole response ininterfacial stress of displacement. It is shown in the limit as s<<s1 that in the inner problemsthe fluid and solid pieces uncouple in a particularly convenientmanner allowing analytical solutions to be deduced. These arethen matched with appropriate outer solutions.     

Photoluminescence of bridged polysilsesquioxanes containing urea groups: Doping with Safranine‐O to generate red‐light emission

Bridged polysilsesquioxanes containing urea groups (ureasils) exhibit a broad photoluminescent emission in the visible spectrum. For a particular bridged polysilsesquioxane synthesized by the hydrolytic condensation of a precursor prepared by reaction of 4,4′‐[1,3 phenylenebis‐(1‐methylethylidene)]bis(aniline) (BSA) with 3‐(isocyanatepropyl)triethoxysilane (IPTES), we show that the broad photoluminescent band could be transformed into a relatively narrow emission band located in the red region of the spectra, by doping with Safranine‐O. The spectral overlap between the host emission and the dye absorption generated an efficient energy transfer process (antenna effect). Absorption, emission, and triplet–triplet absorption spectra revealed an efficient dispersion of the dye in the ureasil as well as the presence of strong host‐guest specific interactions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 289–296, 2008     

Essential Work of Fracture of photo-oxidized LDPE/EVA Films

The Essential Work of Fracture approach (EWF) was used to determine how UV-C irradiation alters the fracture behaviour of LDPE/EVA films. Complementary characterization was performed by FTIR, DSC, TOM, and uniaxial tensile testing. The crosslinking reactions that govern photo-oxidation process at initial stage of exposure stiffened the amorphous phase of the polymer, leading to films with enhanced elastic modulus, yield stress and ultimate strength, but impaired strain at break. In the fracture experiments carried out on films irradiated within 0 and 5 days, EWF methodology requirements were met and the corresponding fracture toughness parameters (w_e and βw_p ) turned out to be sensitive to UV-C irradiation. Longer irradiation time triggered the development of microcracks, which not allowed further stable crack growth and invalidated the application of EWF approach.     

B and collider physics: Working group report

This report summarises the work done during WHEPP-6 (Institute of Mathematical Sciences, Chennai, India, Jan 3–15, 2000) in Working group on ‘B and collider physics’.