Transverse Spin Physics at COMPASS

The investigation of transverse spin and transverse momentum effects in deep inelastic scattering is one of the key physics programs of the COMPASS collaboration. Three channels have been analyzed at COMPASS to access the transversity distribution function: The azimuthal distribution of single hadrons, involving the Collins fragmentation function, the azimuthal dependence of the plane containing hadron pairs, involving the two-hadron interference fragmentation function, and the measurement of the transverse polarization of Lambda hyperons in the final state. Azimuthal asymmetries in unpolarized semi-inclusive deep-inelastic scattering give important information on the inner structure of the nucleon as well, and can be used to estimate both the quark transverse momentum k_T in an unpolarized nucleon and to access the so-far unmeasured Boer-Mulders function. COMPASS has measured these asymmetries using spin-averaged 6LiD data.Comment: Proceedings of QCD10 conference, Montpellie

Poprečni spinski i poprečni impulsni učinci pri COMPASSu

(on behalf of the COMPASS collaboration) The investigation of transverse spin and transverse momentum effects in deep inelastic scattering is one of the key physics programs of the COMPASS collaboration. In the years 2002−2004, COMPASS took 160 GeV muon scattering data on a transversely polarized 6LiD target. In 2007, a transversely polarized NH3 target was used. Three different channels to access the transversity distribution function have been analyzed: the azimuthal distribution of single hadrons, involving the Collins fragmentation function, the azimuthal dependence of the plane containing hadron pairs, involving the two-hadron interference fragmentation function, and the measurement of the transverse polarization of lambda hyperons in the final state. Transverse quark momentum effects in a transversely polarized nucleon have been investigated by measuring the Sivers distribution function. Azimuthal asymmetries in unpolarized semi-inclusive deep-inelastic scattering also give important information on the inner structure of the nucleon, and can be used to estimate both the quark transverse momentum in an unpolarized nucleon and to access the so-far unmeasured Boer-Mulders function. COMPASS has measured these asymmetries in 2004 using spin-averaged 6LiD data.Među glavnim istraživačkim programima suradnje COMPASS je proučavanje poprečnih spinskih i poprečnih impulsnih učinaka u duboko-neelastičnom raspršenju. Tijekom 2002. – 2004., COMPASS je sakupio podatke za muonsko raspršenje na 160 GeV na polariziranoj meti 6LiD. U 2007. rabila se polarizirana meta NH3. Analizirana su tri različita kanala radi dobivanja funkcije raspodjele poprečnosti: azimutalna raspodjela za pojedinačne hadrone koja ovisi o Collinsovoj funkciji lomljenja, azimutalna ovisnost ravnine koja sadrži parove hadrona i u kojoj se javlja interferencija funkcije lomljenja, te poprečna polarizacija lambda hyperona u konačnom stanju. Istraživali su se učinci poprečnih kvarkovskih impulsa u poprečno polarizirnom nukleonu mjerenjem Siversove funkcije. Azimutalne asimetrije u nepolariziranom poluinkluzivnom duboko-neelastičnom raspršenju također daju važne podatke o unutarnjoj strukturi nukleona. Mogu se primijeniti radi procjenjivanja poprečnih impulsa kvarkova u nepolariziranom nukleonu i za određivanje BoerMuldersove funkcije koja dosada nije mjerena. Te je asimetrije odredio COMPASS u 2004. rabeći prosjeke podataka 6LiD mjerenj

Poprečni spinski i poprečni impulsni učinci pri COMPASSu

(on behalf of the COMPASS collaboration) The investigation of transverse spin and transverse momentum effects in deep inelastic scattering is one of the key physics programs of the COMPASS collaboration. In the years 2002−2004, COMPASS took 160 GeV muon scattering data on a transversely polarized 6LiD target. In 2007, a transversely polarized NH3 target was used. Three different channels to access the transversity distribution function have been analyzed: the azimuthal distribution of single hadrons, involving the Collins fragmentation function, the azimuthal dependence of the plane containing hadron pairs, involving the two-hadron interference fragmentation function, and the measurement of the transverse polarization of lambda hyperons in the final state. Transverse quark momentum effects in a transversely polarized nucleon have been investigated by measuring the Sivers distribution function. Azimuthal asymmetries in unpolarized semi-inclusive deep-inelastic scattering also give important information on the inner structure of the nucleon, and can be used to estimate both the quark transverse momentum in an unpolarized nucleon and to access the so-far unmeasured Boer-Mulders function. COMPASS has measured these asymmetries in 2004 using spin-averaged 6LiD data.Među glavnim istraživačkim programima suradnje COMPASS je proučavanje poprečnih spinskih i poprečnih impulsnih učinaka u duboko-neelastičnom raspršenju. Tijekom 2002. – 2004., COMPASS je sakupio podatke za muonsko raspršenje na 160 GeV na polariziranoj meti 6LiD. U 2007. rabila se polarizirana meta NH3. Analizirana su tri različita kanala radi dobivanja funkcije raspodjele poprečnosti: azimutalna raspodjela za pojedinačne hadrone koja ovisi o Collinsovoj funkciji lomljenja, azimutalna ovisnost ravnine koja sadrži parove hadrona i u kojoj se javlja interferencija funkcije lomljenja, te poprečna polarizacija lambda hyperona u konačnom stanju. Istraživali su se učinci poprečnih kvarkovskih impulsa u poprečno polarizirnom nukleonu mjerenjem Siversove funkcije. Azimutalne asimetrije u nepolariziranom poluinkluzivnom duboko-neelastičnom raspršenju također daju važne podatke o unutarnjoj strukturi nukleona. Mogu se primijeniti radi procjenjivanja poprečnih impulsa kvarkova u nepolariziranom nukleonu i za određivanje BoerMuldersove funkcije koja dosada nije mjerena. Te je asimetrije odredio COMPASS u 2004. rabeći prosjeke podataka 6LiD mjerenj

Spin Physics at COMPASS

The COMPASS experiment is a fixed target experiment at the CERN SPS using muon and hadron beams for the investigation of the spin structure of the nucleon and hadron spectroscopy. The main objective of the muon physics program is the study of the spin of the nucleon in terms of its constituents, quarks and gluons. COMPASS has accumulated data during 6 years scattering polarized muons off a longitudinally or a transversely polarized deuteron (6LiD) or proton (NH3) target. Results for the gluon polarization are obtained from longitudinal double spin cross section asymmetries using two different channels, open charm production and high transverse momentum hadron pairs, both proceeding through the photon-gluon fusion process. Also, the longitudinal spin structure functions of the proton and the deuteron were measured in parallel as well as the helicity distributions for the three lightest quark flavors. With a transversely polarized target, results were obtained with proton and deuteron targets for the Collins and Sivers asymmetries for charged hadrons as well as for identified kaons and pions. The Collins asymmetry is sensitive to the transverse spin structure of the nucleon, while the Sivers asymmetry reflects correlations between the quark transverse momentum and the nucleon spin. Recently, a new proposal for the COMPASS II experiment was accepted by the CERN SPS which includes two new topics: Exclusive reactions like DVCS and DVMP using the muon beam and a hydrogen target to study generalized parton distributions and Drell-Yan measurements using a pion beam and a polarized NH3 target to study transverse momentum dependent distributions.Comment: Proceedings of the Rutherford conference, Manchester, August 2011. Changes due to referees comments implemente

Transversity Signals in Two-Hadron Production at COMPASS

New results on single spin asymmetries of identified charged pion and kaon pairs produced in deep-inelastic scattering of muons on a transversely polarized 6 LiD target are presented. The data were taken in the years 2003 and 2004 with the COMPASS spectrometer at CERN with a 160 GeV muon beam from the CERN SPS accelerator. The asymmetries can be interpreted in the context of transversity as a convolution of the chiral-odd interference fragmentation function H 1 with the transverse spin distribution of quarks ∆T q(x). The measured azimuthal target spin asymmetries on the deuteron are compatible with zero within a small statistical error of about 1%

Do Benefits from Dynamic Tariffing Rise? Welfare Effects of Real-Time Retail Pricing Under Carbon Taxation and Variable Renewable Electricity Supply

We analyze the gross welfare gains from real-time retail pricing in electricity markets where carbon taxation induces investment in variable renewable technologies. Applying a stylized numerical electricity market model, we find a U-shaped association between carbon taxation and gross welfare gains. The benefits of introducing real-time pricing can accordingly be relatively low at relatively high carbon taxes and vice versa. The non-monotonous change in welfare gains can be explained by corresponding changes in the inefficiency arising from “under-consumption” during low-price periods rather than by changes in wholesale price volatility. Our results may cast doubt on the efficiency of ongoing roll-outs of advanced meters in many electricity markets, since net benefits might only materialize at relatively high carbon tax levels and renewable supply shares. © 2019, The Author(s)

Development and Performance Verification of the GANDALF High-Resolution Transient Recorder System

With present-day detectors in high energy physics one often faces fast analog pulses of a few nanoseconds length which cover large dynamic ranges. In many experiments both amplitude and timing information have to be measured with high accuracy. Additionally, the data rate per readout channel can reach several MHz, which leads to high demands on the separation of pile-up pulses. For an upgrade of the COMPASS experiment at CERN we have designed the GANDALF transient recorder with a resolution of 12bit@1GS/s and an analog bandwidth of 500\:MHz. Signals are digitized with high precision and processed by fast algorithms to extract pulse arrival times and amplitudes in real-time and to generate trigger signals for the experiment. With up to 16 analog channels, deep memories and a high data rate interface, this 6U-VME64x/VXS module is not only a dead-time free digitization unit but also has huge numerical capabilities provided by the implementation of a Virtex5-SXT FPGA. Fast algorithms implemented in the FPGA may be used to disentangle possible pile-up pulses and determine timing information from sampled pulse shapes with a time resolution better than 50 ps.Comment: 5 pages, 9 figure

Oceans and space: new frontiers in investment protection?

This article provides background and introduces into the overarching themes of the contributions to the Special Issue dealing with investment protection in areas beyond territorial jurisdiction at sea and in outer space. It explains that fast-paced commercialization, evolving technological advances, and the inevitable need for regulatory intervention make the oceans and space into an increasingly important topic in international investment law. At the same time, investment lawyers, as well as experts in the law of the sea and space law, have largely ignored the legal issues foreign investments raise in these spaces. The article sketches out a framework for addressing the underlying issues from an investment law perspective, pointing out both familiar conceptual approaches and novel challenges

Radial Alignment of Carbon Nanotubes via Dead‐End Filtration

Dead-end filtration is a facile method to globally align single wall carbon nanotubes (SWCNTs) in large area films with a 2D order parameter, S2D, approaching unity. Uniaxial alignment has been achieved using pristine and hot-embossed membranes but more sophisticated geometries have yet to be investigated. In this work, three different patterns with radial symmetry and an area of 3.8 cm2 are created. Two of these patterns are replicated by the filtered SWCNTs and S2D values of ≈0.85 are obtained. Each of the radially aligned SWCNT films is characterized by scanning cross-polarized microscopy in reflectance and laser imaging in transmittance with linear, radial, and azimuthal polarized light fields. The former is used to define a novel indicator akin to the 2D order parameter using Malu's law, yielding 0.82 for the respective film. The films are then transferred to a flexible printed circuit board and terminal two-probe electrical measurements are conducted to explore the potential of those new alignment geometries