G. Nukazuka

Future plannings for the COMPASS polarized target

The COMPASS collaboration performed a polarized Drell-Yan program to measure TMD (Transverse Momentum Dependent) and PDFs (Parton Distribution Functions) in 2015. We will carry out the program for one more year in 2018 to improve the statistics. In the Drell-Yan program a negative pion beam of 190 GeV/c with an intensity of

Production of a polarizable target using mechanical doping method and trial of dynamic nuclear polarization

10^8

Large COMPASS polarized solid state target for Drell-Yan physics

/s will be scattered on a transversely polarized proton target with a length of 110 cm. We also plan to use a transversely polarized deuteron target for SIDIS (Semi-Inclusive-Deep-Inelastic-Scattering) program with muon beam in 2021 just after a long shut down of the CERN accelerators. We will present the improved COMPASS PT system for the 2018 run and present the future plan of the deuteron target in 2021.

A 2.5 m long liquid hydrogen target for COMPASS

Dynamic Nuclear Polarization (DNP) which is often employed for polarized solid targets, needs free electron doping to transfer high electron polarization to target nuclei. A newly proposed “mechanical-doping” method was applied in preparation of a polarized target material. A solid material having been crushed into small particles with a diameter of about 20 nm, is mixed with a free radical. This allows target nuclei to have more chance to interact with the free electrons or polarized nuclei surrounding the small particles. A first DNP test at a magnetic field of 2.5 T and a temperature of 0.9 K was performed with a sample of LaF_{3} processed in the mechanical-doping method to introduce a free radical TEMPO dispersed in ethanol. ^{19}F polarizations of 3.3 % and -2.7 % were achieved. The obtained polarization enhancement for ^{19}F demonstrated effectiveness of the new method.

Cryoprotectant-free high-pressure cooling and dynamic nuclear polarization for more sensitive detection of hydrogen in neutron protein crystallography

In the COMPASS Drell-Yan programme a negative pion beam with momentum of 190 GeV/c and intensity up to 108 particles/s is used. The polarizable solid state NH3 target is placed inside the mixing chamber of a large horizontal helium-3/4 dilution cryostat. A large acceptance superconducting solenoid magnet with a nominal field of 2.5 T is used to polarize the protons by microwave pumping around electron spin frequency. Due to the space needed by the hadron absorber the target platform had to be moved 2.3 m upstream from deep inelastic scattering position of run 2011. The upgrade of the target system and the initial commissioning are presented.