Spectral properties of singular Sturm-Liouville operators with indefinite weight sgn x

We consider a singular Sturm-Liouville expression with the indefinite weight sgn x. To this expression there is naturally a self-adjoint operator in some Krein space associated. We characterize the local definitizability of this operator in a neighbourhood of $\infty$. Moreover, in this situation, the point $\infty$ is a regular critical point. We construct an operator A=(\sgn x)(-d^2/dx^2+q) with non-real spectrum accumulating to a real point. The obtained results are applied to several classes of Sturm-Liouville operators.Comment: 21 pages, LaTe

Development and test results of a readout chip for the GERDA experiment

This paper describes the F-CSA104 architecture and its measurement results. The F-CSA104 is for γ spectroscopy with Ge detectors. It is a low noise, fully integrated, four channel XFAB 0.6μm CMOS technology ASIC, that has been developed for the GERDA experiment. Each channel contains a charge sensitive preamplifier (CSA) followed by a 11.7MHz differential line driver. It has been particularly designed to operate in liquid argon (T = 87K/-186°C) and to have a measuring sensitivity of 660e- with an ENC of 110e-, after offline filtering with 10μs shaping, when connected to a 30pF load. Special techniques are used to improve the SNR such as a large input PMOS FET, an integrated 500MΩ CSA feedback resistor and a noise degeneration drain resistor

LUX -- A Laser-Plasma Driven Undulator Beamline

The LUX beamline is a novel type of laser-plasma accelerator. Building on the joint expertise of the University of Hamburg and DESY the beamline was carefully designed to combine state-of-the-art expertise in laser-plasma acceleration with the latest advances in accelerator technology and beam diagnostics. LUX introduces a paradigm change moving from single-shot demonstration experiments towards available, stable and controllable accelerator operation. Here, we discuss the general design concepts of LUX and present first critical milestones that have recently been achieved, including the generation of electron beams at the repetition rate of up to 5 Hz with energies above 600 MeV and the generation of spontaneous undulator radiation at a wavelength well below 9 nm.Comment: submitte

Enhanced Radiation Hardness and Faster Front Ends for the Beetle Readout Chip

This paper summarizes the recent progress in the development of the 128 channel pipelined readout chip Beetle, which is intended for the silicon vertex detector, the inner tracker, the pile-up veto trigger and the RICH detectors of LHCb. Deficiencies found in the front end of the Beetle Version 1.0 and 1.1 chips resulted in the submissions of BeetleFE 1.1 and BeetleFE 1.2, while BeetleSR 1.0 implements test circuits to provide future Beetle chips with logic circuits hardened against single event upset (SEU). Section I. motivates the development of new front ends for the Beetle chip, and section II. summarizes their concepts and construction. Section III. reports preliminary results from the BeetleFE 1.1 and BeetleFE 1.2 chips, while section IV. describes the BeetleSR 1.0 chip. An outlook on future test and development of the Beetle chip is given in section V

Transport strategy in Scotland since devolution

This article critically reviews how the Scottish Executive's approach to transport has developed since devolution. Although there is much to commend, a number of concerns can be identified, including the possibility that a number of strategic infrastructure schemes appear to have been approved on political rather than on technical grounds. It is difficult to know whether the current set of transport infrastructure investment plans represents good value for public money

PT symmetry, Cartan decompositions, Lie triple systems and Krein space related Clifford algebras

Gauged PT quantum mechanics (PTQM) and corresponding Krein space setups are studied. For models with constant non-Abelian gauge potentials and extended parity inversions compact and noncompact Lie group components are analyzed via Cartan decompositions. A Lie triple structure is found and an interpretation as PT-symmetrically generalized Jaynes-Cummings model is possible with close relation to recently studied cavity QED setups with transmon states in multilevel artificial atoms. For models with Abelian gauge potentials a hidden Clifford algebra structure is found and used to obtain the fundamental symmetry of Krein space related J-selfadjoint extensions for PTQM setups with ultra-localized potentials.Comment: 11 page

n-XYTER: A CMOS read-out ASIC for a new generation of high rate multichannel counting mode neutron detectors

For a new generation of 2-D neutron detectors developed in the framework of the EU NMI3 project DETNI [1], the 128-channel frontend chip n-XYTER has been designed. To facilitate the reconstruction of single neutron incidence points, the chip has to provide a spatial coordinate (represented by the channel number), as well as time stamp and amplitude information to match the data of x- and y-coordinates. While the random nature of the input signals calls for self-triggered operation of the chip, on-chip derandomisation and sparsi cation is required to exploit the enormous rate capability of these detectors ( 4 106cm2s1). The chosen architecture implements a preampli er driving two shapers with di erent time constants per channel. The faster shaper drives a single-pulse discriminator with subsequent time-walk compensation. The output of this circuit is used to latch a 14-bit time stamp with a 2 ns resolution and to enable a peak detector circuit fed by the slower shaper branch. The analogue output of the peak detector as well as the time stamp are stored in a 4-stage FIFO for derandomisation. The readout of these FIFOs is accomplished by a token-ring based multiplexer working at 32 MHz, which accounts for further derandomisation, sparsi cation and dynamic bandwidth distribution. The chip was submitted for manufacturing in AMS's C35B4M3 0.35µm CMOS technology in June 2006

The LQG -- String: Loop Quantum Gravity Quantization of String Theory I. Flat Target Space

We combine I. background independent Loop Quantum Gravity (LQG) quantization techniques, II. the mathematically rigorous framework of Algebraic Quantum Field Theory (AQFT) and III. the theory of integrable systems resulting in the invariant Pohlmeyer Charges in order to set up the general representation theory (superselection theory) for the closed bosonic quantum string on flat target space. While we do not solve the, expectedly, rich representation theory completely, we present a, to the best of our knowledge new, non -- trivial solution to the representation problem. This solution exists 1. for any target space dimension, 2. for Minkowski signature of the target space, 3. without tachyons, 4. manifestly ghost -- free (no negative norm states), 5. without fixing a worldsheet or target space gauge, 6. without (Virasoro) anomalies (zero central charge), 7. while preserving manifest target space Poincar\'e invariance and 8. without picking up UV divergences. The existence of this stable solution is exciting because it raises the hope that among all the solutions to the representation problem (including fermionic degrees of freedom) we find stable, phenomenologically acceptable ones in lower dimensional target spaces, possibly without supersymmetry, that are much simpler than the solutions that arise via compactification of the standard Fock representation of the string. Moreover, these new representations could solve some of the major puzzles of string theory such as the cosmological constant problem. The solution presented in this paper exploits the flatness of the target space in several important ways. In a companion paper we treat the more complicated case of curved target spaces.Comment: 46 p., LaTex2e, no figure

Testing the Master Constraint Programme for Loop Quantum Gravity III. SL(2,R) Models

This is the third paper in our series of five in which we test the Master Constraint Programme for solving the Hamiltonian constraint in Loop Quantum Gravity. In this work we analyze models which, despite the fact that the phase space is finite dimensional, are much more complicated than in the second paper: These are systems with an SL(2,\Rl) gauge symmetry and the complications arise because non -- compact semisimple Lie groups are not amenable (have no finite translation invariant measure). This leads to severe obstacles in the refined algebraic quantization programme (group averaging) and we see a trace of that in the fact that the spectrum of the Master Constraint does not contain the point zero. However, the minimum of the spectrum is of order $\hbar^2$ which can be interpreted as a normal ordering constant arising from first class constraints (while second class systems lead to $\hbar$ normal ordering constants). The physical Hilbert space can then be be obtained after subtracting this normal ordering correction.Comment: 33 pages, no figure