Performance Testing of a Novel Off-plane Reflection Grating and Silicon Pore Optic Spectrograph at PANTER

An X-ray spectrograph consisting of radially ruled off-plane reflection gratings and silicon pore optics was tested at the Max Planck Institute for extraterrestrial Physics PANTER X-ray test facility. The silicon pore optic (SPO) stack used is a test module for the Arcus small explorer mission, which will also feature aligned off-plane reflection gratings. This test is the first time two off-plane gratings were actively aligned to each other and with a SPO to produce an overlapped spectrum. The gratings were aligned using an active alignment module which allows for the independent manipulation of subsequent gratings to a reference grating in three degrees of freedom using picomotor actuators which are controllable external to the test chamber. We report the line spread functions of the spectrograph and the actively aligned gratings, and plans for future development.Comment: Draft Version March 19, 201

Dissipation in adiabatic quantum computers: lessons from an exactly solvable model

We introduce and study the adiabatic dynamics of free-fermion models subject to a local Lindblad bath and in the presence of a time-dependent Hamiltonian. The merit of these models is that they can be solved exactly, and will help us to study the interplay between nonadiabatic transitions and dissipation in many-body quantum systems. After the adiabatic evolution, we evaluate the excess energy (the average value of the Hamiltonian) as a measure of the deviation from reaching the final target ground state. We compute the excess energy in a variety of different situations, where the nature of the bath and the Hamiltonian is modified. We find robust evidence of the fact that an optimal working time for the quantum annealing protocol emerges as a result of the competition between the nonadiabatic effects and the dissipative processes. We compare these results with the matrix-product-operator simulations of an Ising system and show that the phenomenology we found also applies for this more realistic case

BeppoSAX Observations of Unprecedented Synchrotron Activity in the BL Lac Object Mkn 501

The BL Lac object Mkn 501, one of the only three extragalactic sources (with Mkn 421 and 1ES 2344+514) so far detected at TeV energies, was observed with the BeppoSAX satellite on 7, 11, and 16 April 1997 during a phase of high activity at TeV energies, as monitored with the Whipple, HEGRA and CAT Cherenkov telescopes. Over the whole 0.1-200 keV range the spectrum was exceptionally hard (alpha =< 1, with F_nu ~ nu^{-alpha}) indicating that the X-ray power output peaked at (or above) ~100 keV. This represents a shift of at least two orders of magnitude with respect to previous observations of Mkn 501, a behavior never seen before in this or any other blazar. The overall X-ray spectrum hardens with increasing intensity and, at each epoch, it is softer at larger energies. The correlated variability from soft X-rays to the TeV band points to models in which the same population of relativistic electrons produces the X-ray continuum via synchrotron radiation and the TeV emission by inverse Compton scattering of the synchrotron photons or other seed photons. For the first time in any blazar the synchrotron power is observed to peak at hard X-ray energies. The large shift of the synchrotron peak frequency with respect to previous observations of Mkn 501 implies that intrinsic changes in the relativistic electron spectrum caused the increase in emitted power. Due to the very high electron energies, the inverse Compton process is limited by the Klein-Nishina regime. This implies a quasi-linear (as opposed to quadratic) relation of the variability amplitude in the TeV and hard X-ray ranges (for the SSC model) and an increase of the inverse Compton peak frequency smaller than that of the synchrotron peak frequency.Comment: 11 pages, Latex, 4 Postscript figures, to appear in The Astrophysical Journal Letter

The Athena x-ray optics development and accommodation

The Athena mission, under study and preparation by ESA as its second Large-class science mission, requires the largest X-ray optics ever flown, building on a novel optics technology based on mono crystalline silicon. Referred to as Silicon Pore Optics technology (SPO), the optics is highly modular and benefits from technology spin-in from the semiconductor industry. The telescope aperture of about 2.5 meters is populated by around 700 mirror modules, accurately co-aligned to produce a common focus. The development of the SPO technology is a joint effort by European industrial and research entities, working together to address the challenges to demonstrate the imaging performance, robustness and efficient series production of the Athena optics. A technology development plan was established and is being regularly updated to reflect the latest developments, and is fully funded by the ESA technology development programmes. An industrial consortium was formed to ensure coherence of the individual technology development activities. The SPO technology uses precision machined mirror plates produced using the latest generation top quality 12 inch silicon wafers, which are assembled into rugged stacks. The surfaces of the mirror plates and the integral support structure is such, that no glue is required to join the individual mirror plates. Once accurately aligned with respect to each other, the surfaces of the mirror plates merge in a physical bonding process. The resultant SPO mirror modules are therefore very accurate and stable and can sustain the harsh conditions encountered during launch and are able to tolerate the space environment expected during operations. The accommodation of the Athena telescope is also innovative, relying on a hexapod mechanism to align the optics to the selected detector instruments located in the focal plane. System studies are complemented by dedicated technology development activities to demonstrate the capabilities before the adoption of the Athena mission

Silicon pore optics mirror modules for inner and outer radii

Athena (Advanced Telescope for High Energy Astrophysics) is an x-ray observatory using a Silicon Pore Optics telescope and was selected as ESA's second L-class science mission for a launch in 2028. The x-ray telescope consists of several hundreds of mirror modules distributed over about 15-20 radial rings. The radius of curvature and the module sizes vary among the different radial positions of the rings resulting in different technical challenges for mirror modules for inner and outer radii. We present first results of demonstrating Silicon Pore Optics for the extreme radial positions of the Athena telescope. For the inner most radii (0.25 m) a new mirror plate design is shown which overcomes the challenges of larger curvatures, higher stress values and bigger plates. Preliminary designs for the mounting system and its mechanical properties are discussed for mirror modules covering all other radial positions up to the most outer radius of the Athena telescope

Simulating the optical performances of the ATHENA x-ray telescope optics

The ATHENA (Advanced Telescope for High Energy Astrophysics) X-ray observatory is an ESA-selected L2 class mission. In the proposed configuration, the optical assembly has a diameter of 2.2 m with an effective area of 1.4 m2 at 1 keV, 0.25 m2 at 6 keV, and requires an angular resolution of 5 arcsec. To meet the requirements of effective area and angular resolution, the technology of Silicon Pore Optics (SPO) was selected for the optics implementation. The ATHENA's optic assembly requires hundreds of SPOs mirror modules (MMs), obtained by stacking wedged and ribbed silicon wafer plates onto silicon mandrels to form the Wolter-I configuration. Different factors can contribute to limit the imaging performances of SPOs, such as i) diffraction through the pore apertures, ii) plate deformations due to fabrication errors and surface roughness, iii) alignment errors among plates in an MM, and iv) co-focality errors within the MMs assembly. In order to determine the fabrication and assembling tolerances, the impact of these contributions needs to be assessed prior to manufacturing. A set of simulation tools responding to this need was developed in the framework of the ESA-financed projects SIMPOSIuM and ASPHEA. In this paper, we present the performance simulation obtained for the recentlyproposed ATHENA configuration in terms of effective area, and we provide a simulation of the diffractive effects in a pair of SPO MMs. Finally, we present an updated sizing of magnetic diverter (a Halbach array) and the magnetic fields levels that can be reached in order to deviate the most energetic protons out of the detector field