Design, performance, and calculated error of a Faraday cup for absolute beam current measurements of 600-MeV protons

A mobile self-contained Faraday cup system for beam current measurments of nominal 600 MeV protons was designed, constructed, and used at the NASA Space Radiation Effects Laboratory. The cup is of reentrant design with a length of 106.7 cm and an outside diameter of 20.32 cm. The inner diameter is 15.24 cm and the base thickness is 30.48 cm. The primary absorber is commercially available lead hermetically sealed in a 0.32-cm-thick copper jacket. Several possible systematic errors in using the cup are evaluated. The largest source of error arises from high-energy electrons which are ejected from the entrance window and enter the cup. A total systematic error of -0.83 percent is calculated to be the decrease from the true current value. From data obtained in calibrating helium-filled ion chambers with the Faraday cup, the mean energy required to produce one ion pair in helium is found to be 30.76 + or - 0.95 eV for nominal 600 MeV protons. This value agrees well, within experimental error, with reported values of 29.9 eV and 30.2 eV

Lithium-drifted silicon detectors as low-energy photon spectrometers

Fabrication and testing of lithium-drifted detectors as low energy photon spectrometer

Does the UK Local Finance Improvement Trust (Lift)Initiative Improve Risk Management in Public-Private Procurement?

The UK government introduced the Private Finance Initiative (PFI) and, latterly, the Local Improvement Finance Trust (LIFT) in an attempt to improve public service provision. As a variant of PFI, LIFT seeks to create a framework for the effective provision of primary care facilities. Like conventional PFI procurement, LIFT projects involve long-term contracts, complex multi-party interactions and thus create various risks to public sector clients. This paper investigates the advantages and disadvantages of LIFT with a focus on how this approach facilitates or impedes risk management from the public sector client perspective. Our paper concludes that LIFT has a potential for creating additional problems, including the further reduction of public sector control, conflicts of interest, the inappropriate use of enabling funds, and higher than market rental costs affecting the uptake of space in the buildings by local health care providers. However, there is also evidence that LIFT has facilitated new investment and that Primary Care Trusts (PCTs) have themselves started addressing some of the weaknesses of this procurement format through the bundling of projects and other forms of regional co-operation

The limits of market-based governance and accountability - PFI refinancing and the resurgence of the regulatory state

The refinancing of PFI (Private Finance Initiative) projects currently represents one of the most contentious aspects of Public Private Partnership in the UK. The negative publicity associated with UK PFI refinancing deals is associated with two main factors, namely evidence of massive private sector profit making in connection with past refinancing deals, and the ‘failure’ of private sector financiers to share refinancing profits with public sector organisations in line with government recommendations. This paper examines the ongoing ‘dance of non-regulation’ associated with PFI refinancing on the basis of traditional Marxist notions of ‘contradictions of capitalism’. Our analysis commences with the argument that PFI represents a prototypical case of an alliance between finance capital and the state, which has been created with the principal purpose of establishing a new source of profits for the private sector. A Marxist analysis of state-business relationships would predict such an alliance to show tendencies towards instability which could arise from a number of factors. These include, among others, the inherent lack of legitimacy of such an alliance vis a vis established policy goals and the stakeholders associated with them; a lack of a credible regulatory framework which, as a systemic prerequisite of private sector profit making, further exacerbates existing problems of legitimation; and, perhaps most importantly, the potentially self-defeating attempt by capital to maximise gains from the exploitation of the existing alliance without concern for the possibility of a political or regulatory backlash. Examining the recent history of PFI refinancing we find evidence of most of these destabilising tendencies which we expect to trigger calls for a greater regulation of PFI projects in the future

The limits of market-based governance and accountability - PFI refinancing and the resurgence of the regulatory state

The refinancing of PFI (Private Finance Initiative) projects currently represents one of the most contentious aspects of Public Private Partnership in the UK. The negative publicity associated with UK PFI refinancing deals is associated with two main factors, namely evidence of massive private sector profit making in connection with past refinancing deals, and the ‘failure’ of private sector financiers to share refinancing profits with public sector organisations in line with government recommendations. This paper examines the ongoing ‘dance of non-regulation’ associated with PFI refinancing on the basis of traditional Marxist notions of ‘contradictions of capitalism’. Our analysis commences with the argument that PFI represents a prototypical case of an alliance between finance capital and the state, which has been created with the principal purpose of establishing a new source of profits for the private sector. A Marxist analysis of state-business relationships would predict such an alliance to show tendencies towards instability which could arise from a number of factors. These include, among others, the inherent lack of legitimacy of such an alliance vis a vis established policy goals and the stakeholders associated with them; a lack of a credible regulatory framework which, as a systemic prerequisite of private sector profit making, further exacerbates existing problems of legitimation; and, perhaps most importantly, the potentially self-defeating attempt by capital to maximise gains from the exploitation of the existing alliance without concern for the possibility of a political or regulatory backlash. Examining the recent history of PFI refinancing we find evidence of most of these destabilising tendencies which we expect to trigger calls for a greater regulation of PFI projects in the future

How multiplicity determines entropy and the derivation of the maximum entropy principle for complex systems

The maximum entropy principle (MEP) is a method for obtaining the most likely distribution functions of observables from statistical systems, by maximizing entropy under constraints. The MEP has found hundreds of applications in ergodic and Markovian systems in statistical mechanics, information theory, and statistics. For several decades there exists an ongoing controversy whether the notion of the maximum entropy principle can be extended in a meaningful way to non-extensive, non-ergodic, and complex statistical systems and processes. In this paper we start by reviewing how Boltzmann-Gibbs-Shannon entropy is related to multiplicities of independent random processes. We then show how the relaxation of independence naturally leads to the most general entropies that are compatible with the first three Shannon-Khinchin axioms, the (c,d)-entropies. We demonstrate that the MEP is a perfectly consistent concept for non-ergodic and complex statistical systems if their relative entropy can be factored into a generalized multiplicity and a constraint term. The problem of finding such a factorization reduces to finding an appropriate representation of relative entropy in a linear basis. In a particular example we show that path-dependent random processes with memory naturally require specific generalized entropies. The example is the first exact derivation of a generalized entropy from the microscopic properties of a path-dependent random process.Comment: 6 pages, 1 figure. To appear in PNA

The population of deformed bands in 48^{48}Cr by emission of 8^{8}Be from the 32^{32}S + 24^{24}Mg reaction

Using particle-$\gamma$ coincidences we have studied the population of final states after the emission of 2 $\alpha$-particles and of $^{8}$Be in nuclei formed in $^{32}$S+$^{24}$Mg reactions at an energy of $\textrm{E}_{\rm L}(^{32}\textrm{S}) = 130 {\rm MeV}$. The data were obtained in a setup consisting of the GASP $\gamma$-ray detection array and the multidetector array ISIS. Particle identification is obtained from the $\Delta$E and E signals of the ISIS silicon detector telescopes, the $^{8}$Be being identified by the instantaneous pile up of the $\Delta$E and E pulses. $\gamma$-ray decays of the $^{48}$Cr nucleus are identified with coincidences set on 2 $\alpha$-particles and on $^{8}$Be. Some transitions of the side-band with $K^\pi=4^{-}$ show stronger population for $^{8}$Be emission relative to that of 2 $\alpha$-particles (by a factor $1.5-1.8$). This observation is interpreted as due to an enhanced emission of $^{8}$Be into a more deformed nucleus. Calculations based on the extended Hauser-Feshbach compound decay formalism confirm this observation quantitatively.Comment: 17 pages, 9 figures accepted for publication in J. Phys.

The Infrared Nucleus of the Wolf-Rayet Galaxy Henize 2-10

We have obtained near-infrared images and mid-infrared spectra of the starburst core of the dwarf Wolf-Rayet galaxy He 2-10. We find that the infrared continuum and emission lines are concentrated in a flattened ellipse 3-4'' or 150 pc across which may show where a recent accretion event has triggered intense star formation. The ionizing radiation from this cluster has an effective temperature of 40,000 K, corresponding to $30M_\odot$ stars, and the starburst is $0.5-1.5 \times 10^7$ years old.Comment: 17 pages Latex, 7 postscript figures, 1 postscript table, accepted to A

Spin lifetimes and strain-controlled spin precession of drifting electrons in zinc blende type semiconductors

We study the transport of spin polarized electrons in n-GaAs using spatially resolved continuous wave Faraday rotation. From the measured steady state distribution, we determine spin relaxation times under drift conditions and, in the presence of strain, the induced spin splitting from the observed spin precession. Controlled variation of strain along [110] allows us to deduce the deformation potential causing this effect, while strain along [100] has no effect. The electric field dependence of the spin lifetime is explained quantitatively in terms of an increase of the electron temperature.Comment: 5 pages, 6 figure

Dense Molecular Filaments Feeding a Starburst: ALMA Maps of CO(3-2) in Henize 2-10

We present ALMA CO(3-2) observations at 0.3 arcsec resolution of He2-10, a starburst dwarf galaxy and possible high-z galaxy analogue. The warm dense gas traced by CO(3--2) is found in clumpy filaments that are kinematically and spatially distinct. The filaments have no preferred orientation or direction; this may indicate that the galaxy is not evolving into a disk galaxy. Filaments appear to be feeding the active starburst; the velocity field in one filament suggests acceleration onto an embedded star cluster. The relative strengths of CO(3-2) and radio continuum vary strongly on decaparsec scales in the starburst. There is no CO(3--2) clump coincident with the non-thermal radio source that has been suggested to be an AGN, nor unusual kinematics. The kinematics of the molecular gas show significant activity apparently unrelated to the current starburst. The longest filament, east of the starburst, has a pronounced shear of FWHM $\sim40$~\kms\ across its $\sim$50~pc width over its entire $\approx 0.5$ kpc length. The cause of the shear is not clear. This filament is close in projection to a `dynamically distinct' CO feature previously seen in CO(1--0). The most complex region and the most highly disturbed gas velocities are in a region 200~pc south of the starburst. The CO(3--2) emission there reveals a molecular outflow, of linewidth FWZI $\sim$ 120-140 \kms, requiring an energy $\gtrsim 10^{53} \rm~ erg/s$. There is at present {\it no} candidate for the driving source of this outflow.Comment: This was revised 31 October to correct some typos and to replace Figure