Storage Ring EDM Homepage at IUCF

The IUCF Contribution to Deuteron Polarization Measurements

2009 , 2008 , 2007 , 2005 , 2004

2009

We got two weeks of beamtime approved for another run at COSY. After this we have used four out of eight weeks for EDM studies at the Forschungszentrum Jülich.
The goal was to accumulate a larger data set on geometric systematics to the 50 ppm level. We commissioned a super-cycle running mode to suppress the slow drifting we had seen in the last run. The cycle went through in total nine possible different position and angle shifts as well as five different polarization states at the ion source. This automatic mode allowed us to collect two orders of magnitude more data than before. We had to learn now that the systematic effects and procedures are dominated by rate, not geometry. Data was taken in the begin at "high" and later at reduced "low" rates. The effects are linear and correctable. We are working on a model describing the data, including detector asymmetries, tensor polarization, rate effects, and changing beam polarization.

Summary from the run in June 2009.

2008

We had the first two runs approved at COSY for this year, at the Forschungszentrum Jülich in Germany.
We use the detector system from the former experiment EDDA (Excitation Function Data Acquisition designed for Analysis of Phase Shifts) as a mock-up polarimeter. No changes to the operating point or the EDDA electronics were made. We bring our own electronics system to the runs, assembled at the KVI, attach this system to one branch of the signals from the EDDA detector, leaving the existing system in place.
We have demonstrated that one can slowly extract the stored beam onto a thick target and scatter particles into a set of detectors with high efficiency, thereby making possible continuous and statistically precise measurements of the polarization properties of the stored beam.

Summary from the first run in June 2008.

We came back in September to get the first data. The goal was to investigate polarimeter systematic errors, which are especially displacement / angle errors. The Left-Right-asymmetry changes in first order due to errors. The usual remedy is to measure on both sides (Left and Right), flip the initial spin and use the cross ratio formula which cancels first-order errors. We were tracking what happens to the cross ratio while deliberately shifting the beam by an angle or position.

Summary from this run in September 2008.

Recommendations of the COSY PAC 36 meeting in December 2008.

Annual Report 2008 at IUCF

2007

In May 2007 a proposal was presented to the Program Advisory Committee at COSY-Jülich. It outlined several objectives of the work there:

  • Data on deuteron-induced reactions on carbon is scarce in the regime between p = 1.0 - 1.5 GeV/c where we expect the polarimeter on a resonance-method storage ring to operate. In particular, measurements are needed for elastic scattering (including reaction channels with a small Q-value) and the protons from deuteron breakup.
  • The data from Saturne indicates that efficiencies of a few percent are possible with targets several centimeters thick. In order to bring this efficiency to the EDM search, we propose to build annular targets shaped like a thick-walled tube that surrounds the circulating deuteron beam.
  • Continuous polarization measurements of a horizontally-polarized storage ring beam have not been made for the situation where the polarization is rotating rapidly. From that experience, we determined that new data acquisition electronics and computer control is needed. This needs to be developed, installed, and tested.
  • In parallel with the effort to measure a rapidly rotating horizontal polarization, we need to find the best way to produce this state, perhaps by using the RF solenoid presently in place.
  • Studies are needed of measurements of the vertical polarization component in the presence of a rapidly-rotating and large horizontal component whose magnitude varies during the beam store.
    • The proposal was approved, with a first week of beamtime in June 2008.

    Annual Report 2007 at IUCF

    2005

    Second run at the KVI
    Preliminary Data Analysis Report
    To the KVI PAC

    2004

    After a consideration of the concept of the polarimeter and the size of the storage ring, we elected to design for a deuteron momentum of 0.7 GeV/c (126 MeV). Data for deuteron-induced reactions do not exist at this energy, so on October 11-16, 2004, we made broad-spectrum measurements at the KVI in Groningen at 80 and 110 MeV. Large analyzing powers were seen, as expected.

    There are possible avenues to pursue at the KVI for polarimeter development, including the testing of detectors for operation at high rate and the measurement of the analyzing power of a prototype polarimeter. A letter of intent was submitted to the KVI Program Advisory Committee for consideration at their meeting in November, 2004. This proposal received the highest rating from the KVI Program Committee and is now scheduled to run for rate tests in May, 2005.

    The next step will be to design and build a prototype for testing at the COSY storage ring in Jülich, Germany. A letter of intent was presented to the Program Advisory Committee on April 19-20, 2004 outlining the concept of the polarimeter development and the role that COSY could play. The response was favorable; the PAC encouraged us to maintain contact with the committee and bring a full proposal as soon as feasible.

    Last update: August 3, 2009