M. Kuster

The European Photon Imaging Camera on XMM-Newton: The pn-CCD camera

The European Photon Imaging Camera (EPIC) consortium has provided the focal plane instruments for the three X-ray mirror systems on XMM-Newton. Two cameras with a reflecting grating spectrometer in the optical path are equipped with MOS type CCDs as focal plane detectors (Turner 2001), the telescope with the full photon flux operates the novel pn-CCD as an imaging X-ray spectrometer. The pn-CCD camera system was developed under the leadership of the Max-Planck-Institut fur extraterrestrische Physik (MPE), Garching. The concept of the pn-CCD is described as well as the dierent operational modes of the camera system. The electrical, mechanical and thermal design of the focal plane and camera is briefly treated. The in-orbit performance is described in terms of energy resolution, quantum eciency, time resolution, long term stability and charged particle background. Special emphasis is given to the radiation hardening of the devices and the measured and expected degradation due to radiation damage of ionizing particles in the rst 9 months of in orbit operation.

An improved limit on the axion–photon coupling from the CAST experiment

We have searched for solar axions or similar particles that couple to two photons by using the CERN Axion Solar Telescope (CAST) setup with improved conditions in all detectors. From the absence of excess X-rays when the magnet was pointing to the Sun, we set an upper limit on the axion-photon coupling of 8.8 x 10^{-11} GeV^{-1} at 95% CL for m_a<~ 0.02 eV. This result is the best experimental limit over a broad range of axion masses and for m_a<~ 0.02 eV also supersedes the previous limit derived from energy-loss arguments on globular-cluster stars.

Search for Sub-eV Mass Solar Axions by the CERN Axion Solar Telescope with 3He Buffer Gas

S. Aune, K. Barth, A. Belov, S. Borghi, ∗ H. Bräuninger, G. Cantatore, J. M. Carmona, S. A. Cetin, J. I. Collar, T. Dafni, M. Davenport, C. Eleftheriadis, N. Elias, C. Ezer, G. Fanourakis, E. Ferrer-Ribas, P. Friedrich, J. Galán, J. A. Garćıa, A. Gardikiotis, E. N. Gazis, T. Geralis, I. Giomataris, S. Gninenko, H. Gómez, E. Gruber, T. Guthörl, R. Hartmann, † F. Haug, M. D. Hasinoff, D. H. H. Hoffmann, F. J. Iguaz, ‡ I. G. Irastorza, J. Jacoby, K. Jakovčić, M. Karuza, K. Königsmann, R. Kotthaus, M. Krčmar, M. Kuster, 16, § B. Lakić, ¶ J. M. Laurent, A. Liolios, A. Ljubičić, V. Lozza, G. Lutz, † G. Luzón, J. Morales, ∗∗ T. Niinikoski, †† A. Nordt, 16, ‡‡ T. Papaevangelou, M. J. Pivovaroff, G. Raffelt, T. Rashba, H. Riege, A. Rodŕıguez, M. Rosu, J. Ruz, 2 I. Savvidis, P. S. Silva, S. K. Solanki, L. Stewart, A. Tomás, M. Tsagri, ‡‡ K. van Bibber, §§ T. Vafeiadis, 9, 12 J. Villar, J. K. Vogel, 20, ¶¶ S. C. Yildiz, and K. Zioutas 12

Search for solar axions by the CERN axion solar telescope with 3He buffer gas: closing the hot dark matter gap.

Introduction.—The most promising method to searchfor axions and axion-likeparticles (ALPs) [1–4], low-massbosons with a two-photon interaction vertex, is their con-version to photons in macroscopic magnetic fields [5–7].This approach includes the search for solar axions by thehelioscope technique [8–15], photon regeneration exper-iments (“shining light through a wall”) [16–18], axion-photon conversion in astrophysical B fields [19–22], andthe search for galactic axion dark matter [23–27].One limiting factor in any of these efforts is the mo-mentum difference between freely propagating photonsand axions caused by the axion mass m

The x-ray telescope of CAST

The CERN Axion Solar Telescope (CAST) has been in operation and taking data since 2003. The main objective of the CAST experiment is to search for a hypothetical pseudoscalar boson, the axion, which might be produced in the core of the sun. The basic physics process CAST is based on is the time inverted Primakoff effect, by which an axion can be converted into a detectable photon in an external electromagnetic field. The resulting x-ray photons are expected to be thermally distributed between 1 and 7 keV. The most sensitive detector system of CAST is a pn-CCD detector combined with a Wolter I type x-ray mirror system. With the x-ray telescope of CAST a background reduction of more than 2 orders of magnitude is achieved, such that for the first time the axion photon coupling constant gaγγ can be probed beyond the best astrophysical constraints gaγγ < 1 × 10−10 GeV−1.

The variable cyclotron line in GX 301-2

We present pulse phase resolved spectra of the hypergiant high mass X-ray binary GX 301−2. We observed the source in 2001 October with RXTE continuously for a total on-source time of almost 200 ks. We model the continuum with both, a heavily absorbed partial covering model and a reflection model. In either case we find that the well known cyclotron resonant scattering feature (CRSF) at ∼35 keV is - although present at all pulse phases - strongly variable over the pulse: the line position varies by 25% from 30 keV in the fall of the secondary pulse to 38 keV in the fall of the main pulse where it is deepest. The line variability implies that we are seeing regions of magnetic field strength varying between 3.4 × 10 12 G and 4.2 × 10 12 G.

Axion searches in the past, at present, and in the near future

Theoretical axion models state that axions are very weakly-interacting particles. In order to experimentally detect them, the use of colorful and inspired techniques become mandatory. There are a wide variety of experimental approaches that were developed during the last 30 years; most of them make use of the Primakoff effect, by which axions convert into photons in the presence of an electromagnetic field. We review the experimental techniques used to search for axions and will give an outlook on experiments planned for the near future.

The first broad-band X-ray images and spectra of the 30 Doradus region in the LMC

We present the XMM-Newton first light image, taken in January 2000 with the EPIC pn camera during the instruments commissioning phase, when XMM-Newton was pointing towards the Large Magellanic Cloud (LMC). The field is rich in different kinds of X-ray sources: point sources, supernova remnants (SNRs) and diffuse X-ray emission from LMC interstellar gas. The observations are of unprecedented sensitivity, reaching a few 10

Radioactive Decays in Geant4

\sp{32}

Performance of an LPD prototype detector at MHz frame rates under Synchrotron and FEL radiation

erg/s for point sources in the LMC. We describe how these data sets were analysed and discuss some of the spectroscopic results. For the SNR N157B the power law spectrum is clearly steeper than previously determined from ROSAT and ASCA data. The existence of a significant thermal component is evident and suggests that N157B is not a Crab-like but a composite SNR. Most puzzling is the spectrum of the LMC hot interstellar medium, which indicates a significant overabundance of Ne and Mg of a few times solar.