Narrow Results

Feasibility studies using 0.97-GeV/c polarized deuterons to determine the suitability of storage rings in the search for intrinsic electric dipole moments have led to new developments in storage ring polarimeters. Efficiency has increased with the use of thick carbon targets. The calibration of the effects of geometric and rate-dependent errors has made possible the subtraction of these systematic errors, resulting in sensitivities at or below 10${}^{-5}$ to polarization changes during the time of the store. Tagging polarimeter events with the clock time had made available the turn number for each event, making possible longitudinal profile and horizontal polarization measurements. These have been used to explore the correction of second-order contributions to decoherence using sextupole fields, yielding horizontal polarization lifetimes as long as 20 minutes. Such studies may be extended to protons and ³He.

We present a recent upgradation of the ARIES IMaging POLarimeter (AIMPOL) mounted on the 104cm Sampurnanand telescope of ARIES, Nainital since 2004. AIMPOL is upgraded by replacing the older detector with a new CCD, Pylon 1300B and the older sliding filter assembly with an automatic wheel filter assembly. A characterization of this CCD is performed and several CCD parameters like gain, read-out noise, dark current, and linearity are verified. The average value of the bias offset is measured to be ∼600 ADU whereas the dark current is measured to be 0.2e⁻/pixel/h at $-120^{\circ }$C. The CCD can be operated safely between $-70^{\circ }$ C to $-120^{\circ }$C due to the almost constant dark current in this temperature range. The nonlinearity of the CCD is measured to be ∼2%, which is suitable for scientific observations. A few polarimetric observations are also taken using the upgraded AIMPOL. The degree of polarization and position angle of a few standard polarized stars are found to be similar to their standard and previously observed values.

The chirality (of Greek χείρ, ch[e]ir: hand) is a fundamental symmetry property of three-dimensional objects. Your two hands are not superimposable. They are mirror images of each other. They are therefore chiral (Figure 10.1). The chirality of your right hand can be seen by trying to put it in a glove for your left hand. The same can be seen by trying to put your left hand into a glove for your right hand. The same experience can be done while putting on shoes. Normally you are not comfortable after exchanging the shoe for the left foot with the one for the right foot…

A Polarized Internal gas Target (PIT) has been developed for the ANKE spectrometer at COSY. After its first installation at the ANKE target position in summer 2005, commissioning studies were carried out. In March 2006, the first single polarization measurements with the polarized hydrogen beam from an Atomic Beam Source (ABS) were performed. The beam was injected into a storage cell made from aluminum foil. The data analysis showed that the events from the extended gas target can be clearly identified in the ANKE forward detection system. Using unpolarized nitrogen, the background from the cell walls could be determined as well. The thickness of the gas in the storage cell with the hydrogen atoms in hyperfinestate |1〉 was measured as 2 × 10¹³ atoms/cm². The ABS jet target thickness was (1.5 ± 0.1) × 10¹¹ atoms/cm². In November 2006, the commissioning of a Silicon Tracking Telescope (STT) was successfully finished. In the following beam time in January 2007, a new storage cell made from aluminum coated with teflon was used together with the STT. The Lamb-shift polarimeter (LSP) was mounted below the target chamber to allow online tuning of the transition units and monitoring of the ABS jet polarization. A first double-polarized experiment was performed in January 2007. The results will be presented.