Test beam results of ATLAS Pixel Sensors

Silicon pixel detectors produced according to the ATLAS Pixel Detector design were tested in a beam at CERN in the framework of the ATLAS collaboration. The detectors used n+/n sensors with oxygenated silicon substrates. The experimental behaviour of the detectors after irradiation to 1.1 10**15 n_eq/cm**2 and 600 kGy is discussed. At the sensor bias voltage of 600 V the depleted depth is measured to be 229 um, the mean collected charge is 20000 electrons, the detection efficiency is 98.2% and the spatial resolution is 9.6 umComment: 8 pages, 6 figures, Pixel2002 conferenc

Searches for supersymmetry with the ATLAS detector

First ATLAS searches for signals of Supersymmetry in protonproton collisions at the LHC are presented. These searches are performed with the full data sample recorded in 2010, corresponding to an integrated luminosity of 35 pb−1. Results for various channels with large missing transverse energy and different lepton and jet multiplicities are reported. A search for long-lived strongly interacting particles is also presented. Good consistency with the Standard Model prediction has been found in all channels; limits on squark and gluino masses are derived, which considerably improved previous results

A study on the detection of a light stop squark with the ATLAS Detector at the LHC

The search for light supersymmetric partners of the top quark (stop squark) could result into the early discovery of physics beyond the Standard Model at the LHC. We present here a detailed analysis based on a parametrized simulation of the ATLAS detector. We study a benchmark model in the framework of the Minimal Supersymmetric Standard Model, with a stop squark lighter than the top quark, yielding a final state similar to the one for $t\bar{t}$ production. It is demonstrated that a signal for the stop squark can be extracted in this case, and the kinematic features of the stop decay studied. A technique to subtract the SM background based on the data is developed to achieve this result

Single top production in the tt-channel at LHC: a realistic test of electroweak models

We compute the complete electroweak one-loop effect on the process of $t$-channel single top production at LHC in the Standard Model and in the MSSM within the mSUGRA symmetry breaking scheme. We find that the one-loop electroweak SM effect is large, and decreases the cross section of an amount that is of the same size as that of the NLO QCD one. The genuine SUSY effect in the mSUGRA scheme, for a general choice of benchmark points, is rather small. It might become large and visible in more general scenarios around thresholds involving light stop and neutralino mass values.Comment: 28 pages, 10 eps figure

Haitallisten vieraiden kala-, rapu- ja nisäkäslajien leviäminen, tietoisuuden lisääminen ja hallinta

Työssä kerättiin tietoa mm. hopearuutanan, mustatäplätokon, puronieriän, täpläravun, rapuruton, minkin, supikoiran, amerikanmajavan ja valkohäntäkauriin tilanteesta. Hopearuutanan ja mustatäplätokon levittäytymisestä ja populaatioista kerättiin laaja aineisto. Vieraiden nisäkäslajien haittavaikutusten laajuutta arvioitiin supikoiran ja minkin osalta. Arviointiin käytettiin RKTL:ssa koottuja aineistoja, kuten saalistietoja, peltokolmio- ja riistakolmioaineistoja sekä kala-atlastietoja. Osa tiedoista on koottu julkaistuista aineistoista, osa vielä julkaisemattomista tai valmisteilla olevista materiaaleista. Vieraslajitietoisuuden lisäämiseksi ja uusien havaintojen keräämiseksi vieraslajeista tiedottamista on lisättävä sekä mediassa että kohdennetusti asiantuntijoille. Vieraslajit.fi -portaali tarjoaa hyvän kanavan tähän, mutta sen kehittämistä on edelleen syytä jatkaa. Vieraslajien levinneisyyden muutokset ja niiden elinympäristössään aiheuttamat muutokset saattavat olla nopeita. Esimerkiksi kalojen esiintymisen ja runsastumisen muutoksia olisi seurattava vuosittain. Erityistä huomiota tulisi kiinnittää leviämisvaiheen varhaisiin signaaleihin, kuten yksittäisiin havaintoihin uusista lajeista. Mustatäplätokon ja hopearuutanan todettiin aiheuttavan haittaa alkuperäisille lajeille ja ekosysteemitason muutoksia. Haittojen minimoimiseksi olisi ryhdyttävä välittömiin toimenpiteisiin lajien sisävesiin leviämisen estämiseksi. Useimmiten vieraslajien leviämistä ei voida estää, mutta tietoisuuden lisäämisellä ja asettautumiseen vaikuttavilla säätelytoimenpiteillä kyetään hidastamaan muutoksia. Pääasiassa laivojen painolastivesien mukana leviävien merilajien asettautumismahdollisuuksiin on mahdollista puuttua painolastivesisopimuksella. Sisävesien järvialtailla ja virtavesissä on paikallisilla ratkaisuilla, riskinarvioinneilla ja päätöksillä helpommin saavutettavaa vaikuttavuutta vieraslajien hallinnassa verrattuna merialueisiin. Julkaisussa annetaan lajikohtaisia suosituksia ja ohjeita vieraslajien leviämisen estämiseksi ja torjumiseksi Suomessa. -- Liite 5. HAVINA-loppuraporttiin URN:NBN:fi-fe2014062529465</a

GaN-based radial heterostructure nanowires grown by MBE and ALD

A combination of molecular beam epitaxy (MBE) and atomic layer deposition (ALD) was adopted to fabricate GaN-based core/shell NW structures. ALD was used to deposit a HfO2 shell of onto the MBE grown GaN NWs. Electron transparent samples were prepared by focussed ion beam methods and characterized using state-of-the-art analytical transmission and scanning transmission electron microscopy. The polycrystalline coating was found to be uniform along the whole length of the NWs. Photoluminescence and Raman spectroscopy analysis confirms that the HfO2 ALD coating does not add any structural defect when deposited on the NWs

The effect of experimental pain on short-interval intracortical inhibition with multi-locus transcranial magnetic stimulation

Chronic neuropathic pain is known to alter the primary motor cortex (M1) function. Less is known about the normal, physiological effects of experimental neurogenic pain on M1. The objective of this study is to determine how short-interval intracortical inhibition (SICI) is altered in the M1 representation area of a muscle exposed to experimental pain compared to SICI of another muscle not exposed to pain. The cortical representation areas of the right abductor pollicis brevis (APB) and biceps brachii (BB) muscles of 11 subjects were stimulated with a multi-locus transcranial magnetic stimulation device while the resulting motor-evoked potentials (MEPs) were recorded with electromyography. Single- and paired-pulse TMS was administered in seven conditions, including one with the right hand placed in cold water. The stimulation intensity for the conditioning pulses in the paired-pulse examination was 80% of the resting motor threshold (RMT) of the stimulated site and 120% of RMT for both the test and single pulses. The paired-pulse MEP amplitudes were normalized with the mean amplitude of the single-pulse MEPs of the same condition and muscle. SICI was compared between conditions. After the cold pain, the normalized paired-pulse MEP amplitudes decreased in APB, but not in BB, indicating that SICI was potentially increased only in the cortical area of the muscle subjected to pain. These data suggest that SICI is increased in the M1 representation area of a hand muscle shortly after exposure to pain has ended, which implies that short-lasting pain can alter the inhibitory balance in M1.Peer reviewe