A simple method to determine charge-dependent curvature biases in track reconstruction in hadron collider experiments

A new data-driven method, using $$Z\rightarrow \mu ^+\mu ^-$$ Z → μ + μ - decays, is proposed to correct for charge-dependent curvature biases in spectrometer experiments at hadron colliders. The method is studied assuming a detector with a “forward-spectrometer” geometry similar to that of the LHCb experiment, and is shown to reliably control several simplified detector mis-alignment configurations. The applicability of the method for use in measurements of precision electroweak observables is evaluated.

$$K^{+}\Lambda $$ photoproduction at forward angles and low momentum transfer

Abstract$$\gamma p \rightarrow K^{+} \Lambda $$ γ p → K + Λ differential cross sections and recoil polarisation data from threshold for extremely forward angles are presented. The measurements were performed at the BGOOD experiment at ELSA, utilising the high angular and momentum resolution forward spectrometer for charged particle identification. The high statistics and forward angle acceptance enables the extraction of the cross section as the minimum momentum transfer to the recoiling hyperon is approached.

η’ beam asymmetry at threshold using the BGO-OD experiment

The unexpected nodal structure of the beam asymmetry recently reported by the GRAAL collaboration in η′ photoproduction very close to threshold could be explained by a previously unobserved narrow resonance. The BGO-OD experiment is ideally suited to verify this measurement via the detection of forward going charged particles which in the threshold region of interest allows the identification of the reaction γp → η′ p solely based on the proton going in the forward direction. This yields unprecedented statistics if, in the missing mass analysis of the η′ meson, the background can be sufficiently well controlled. Preliminary results using a linearly polarised photon beam are shown. The reaction γp → η′ p was identified in the BGO forward spectrometer, with simulated data used to seperate signal and background.

ACCURATELY CALCULATING THE SOLAR ORIENTATION OF THE TIANGONG-2 ULTRAVIOLET FORWARD SPECTROMETER

The Ultraviolet Forward Spectrometer is a new type of spectrometer for monitoring the vertical distribution of atmospheric trace gases in the global middle atmosphere. It is on the TianGong-2 space laboratory, which was launched on 15 September 2016. The spectrometer uses a solar calibration mode to modify its irradiance. Accurately calculating the solar orientation is a prerequisite of spectral calibration for the Ultraviolet Forward Spectrometer. In this paper, a method of calculating the solar orientation is proposed according to the imaging geometric characteristics of the spectrometer. Firstly, the solar orientation in the horizontal rectangular coordinate system is calculated based on the solar declination angle algorithm proposed by Bourges and the solar hour angle algorithm proposed by Lamm. Then, the solar orientation in the sensor coordinate system is achieved through several coordinate system transforms. Finally, we calculate the solar orientation in the sensor coordinate system and evaluate its calculation accuracy using actual orbital data of TianGong-2. The results show that the accuracy is close to the simulation method with STK (Satellite Tool Kit), and the error is not more than 2 %. The algorithm we present does not need a lot of astronomical knowledge, but only needs some observation parameters provided by TianGong-2.

Test of Time-Reversal Invariance at COSY (TRIC)

At the Cooler Synchrotron COSY a novel (P-even, T-odd) null test of time-reversal invariance to an accuracy of 10[Formula: see text] is planned as an internal target transmission experiment. The parity conserving time-reversal violating observable is the total cross-section asymmetry A[Formula: see text]. This quantity is measured using a polarized proton beam with an energy of 135 MeV and an internal tensor polarized deuteron target from the PAX atomic beam source. The reaction rate will be determined by the lifetime of the beam. Consequently, the accuracy of the current measurement of the circulating proton beam is crucial for this experiment. Thus, the cooler synchroton ring serves as an ideal forward spectrometer, as a detector, and an accelerator.