Antiproton Physics Experiments

1. Antiproton Sources Past and Current Fermilaband CERN have operated the only antiproton sources. Currently these sources are used for the Tevatron and low energy trapping programs, respectively. Previously, both laboratories have hosted internal gas jet target experiments which focused upon precision measurements of Charmonium. As can be seen, the Fermilab Antiproton Source has been increasing the yearly yield and is far more productive Antiproton Source The beam energy is scanned across the resonance while the detector acts like a big scalar counting final states. The Accumulator is the spectrometer: the systematics of the Mass and Width determination come from knowledge of the beam profiles and the detector relative efficiencies for each scan Accumulator Ring (Inner Ring) Debuncher Ring (Outer Ring) Yearly Antiproton Production e10 Antiprotons Breit-Wigner line shape Convolution results in the observed cross section E760/E835: Charmonium studies and continuum cross section measurements Year E835 Beam Scan of ψ(2S) PRECISION Future Fermilab’s Antiproton Source could be used for experiments after Run II. The CERN Antiproton Decelerator program is uncertain after 2010. Gesellschaft für Schwerionenforschung (GSI) in Darmstadt, Germany is to start construction of the Facility for Antiproton and Ion Research (FAIR). The plans are to support a low energy (trapping) and medium energy antiproton program (HESR). The accumulation rings will be used for antiprotons and ion running. Below is a comparison of possible medium energy programs for what Fermilab has achieved and the design of GSI FAIR. Beam Profiles APEX: Antiproton Lifetime Experiment HBAR: Production of Relativistic Antihydrogen Most precise measurement of the ψ width despite much smaller statistics than e+e- E760 & E835 PRECISION Resonance parameters can be determined from interference between a continuum process and the resonance. The continuum “amplifies” the resonance E835 example in 4 photons pp c0  , /, π0π0 Should expand interference analyses to more channels; in particular pp at 90o 110 <68 [1012] Δp/p [10-5] AP50 Experiment Area Antiproton Physics Experiments Past Fermilab Accumulator Experiments Precision M & Γ Measurements PRECISION

2. Pbar Physics in the Accumulator Charmonium:Precision measurements of the masses and widths are still desirable for the understanding of QCD. All of the Charmonium states -- c(1S0), J/(3S0), hc(1P1),0(3P0),1(3P1),2(3P2),c/(21S0), /(23S0) -- can be made directly in antiproton-proton annihilations by scanning the beam energy through an internal hydrogen target. Scanning method and some previous precision measurements are elsewhere on this poster. See upper left boxes for some other measurements to be made. XYZ States:Precision measurements of the mass, width and angular distributions will help determine whether each state is Charmonium or an exotic state. See upper right boxes for some discussion. Continuum Processes:Cross sections of different final states as a function of Ecm and Dalitz analyses are of interest. The former includes tests of scaling laws, measurement of the Proton Time-like Form Factor, and associated production of Charmonium; the latter can be used to add to the knowledge of light quark resonances. See lower left boxes for some measurements. Searches/COnfirmations:Excited Charmonium states, exotics, glue-balls and hybrids. Partial Rate Asymmetries of Hyperon decays:CP violation can be studied in Ω± ΛK±andΩ±Ξ0± decays. Clean set of Ω+ Ω-can be produced in interactions of antiproton beam and an internal hydrogen target where the 2MΩ < Ecm < 2MΩ+M. Rare Hyperon Decays:HyperCP observed the rare Σ+p μ+μ- decay. The dimuon mass for the three events suggest a resonance. Search for other rare hyperon decays can discover/ confirm a new low mass state Relativistic Antihydrogen:A thin foil inserted into the halo beam can increase the production of relativistic Antihydrogen (~ Z2). A measurement of the Lamb shift is possible. Open Charm:Investigation of the charm mesons about different thresholds is possible. There is potential for competitive measurements of mixing and possible CP violation. Different Nuclear Targets: Charmonium production via the antiproton beam interacting with different internal nuclear targets can be done. Polarized Hydrogen Target: Angular distributions of different final states based upon different polarizations of the Target. In particular, the determination of the magnetic and electric contributions to the Proton Time-like form factor. c/(21S0) PDG M = 3637 ±4 MeV Г = 14 ± 7 MeV 1P1 or hc JPC = 1+- The hc mass is important to understanding hyperfine splitting. The hc width has not been measured Decays of X(3872) into Charmonium or Charm Mesons appear to result in different masses. The Г(s) have not been measured. Can be done in the Accumulator. The precision of the mass and width of the c needs to be improved. E760 & E835 only reported pp  c γγ. Need to observe in more channels. pp 6γ Dalitz Analyses Antiproton Physics Experiments A listing of all of the XYZ states that have been found . The largest center of mass energy that the Accumulator beam interacting with an internal target is A little more than 4.3GeV. The rate of formation in pp is not known since the only the states listed have been seen. More Antiproton Physics Low Energy & Trapping:Antiprotons could be transferred from the Accumulator to the Main Injector and then decelerated. Beam could then be extracted into a low energy ring for further deceleration and cooling or through a energy degrader system. Many possible small experiments could be done: Trapping Antiprotons Antihydrogen Production Antihydrogen Trapping Antihydrogen Spectroscopy Antihydrogen Gravity Measurement Antiprotonic Helium Spectroscopy Antiprotons as Hadronic Probes Medium Energy Ring:Antiprotons could be transferred from the Accumulator to a new medium energy ring designed to ramp; incorporate electron cooling to further decrease the beam size/spread; and include experiment area(s). Moving the experiment from AP50 to a new ring would allow the Accumulator to stack full time increasing the number of available antiprotons significantly. With a larger range of beam momenta, studies of all of the XYZ states would be possible as well as a wider search for Hybrids and Glueballs. Bottomonium:Precision measurements of the mass, width and angular distributions could be determined for all Bottomonium States. One could envision either a small collider (asymmetric?) or an internal target (beam momenta 50-70GeV/c)

3. The precision of the mass and width of the c needs to be improved E760 & E835 only reported pbarp2photons Need to observe in more channels X(3872) seen also in charm meson channels with a slightly different mass PDG M = 3637 ± 4 MeV Г = 14 ± 7 MeV 00 0 1P1 or hc JPC = 1+- The hc mass is important to understanding hyperfine splitting. The hc width has not been measured Antiproton Physics Experiments X(3872) seen in several J/ channels

4. Precision M & Γ Measurements Antiproton Sources Past Accumulator Experiments Past and Current Fermilaband CERN have operated the only antiproton sources. Currently these sources are used for the Tevatron and low energy trapping programs respectively. Previously, both laboratories have hosted internal gas jet target experiments which focused upon precision measurements of Charmonium. As can be seen, the Fermilab Antiproton Source has been increasing the yearly yield and is far more productive The beam energy is scanned across the resonance while the detector acts like a big scalar counting final states. The Accumulator is the spectrometer: the systematics of the Mass and Width determination come from knowledge of the beam profiles and the detector relative efficiencies for each scan Antiproton Source Accumulator Ring (inner Ring) Debuncher Ring (outer Ring) Yearly Antiproton Production e10 Antiprotons The Fermilab Accumulator has hosted three successful experiments in the AP50 straight section -- E760/E835: Charmonium studies and continuum cross section measurements APEX: Antiproton Lifetime Experiment HBAR: Production of Relativistic Antihydrogen Breit-Wigner line shape Convolution results in the observed cross section Year E835 Beam Scan of ψ(2S) PRECISION Future Fermilab’s Antiproton Source could be used for experiments after Run II. The CERN Antiproton Decelerator program is uncertain after 2010. Gesellschaft für Schwerionenforschung (GSI) in Darmstadt, Germany is to start construction of the Facility for Antiproton and Ion Research (FAIR). The plans are to support a low energy (trapping) and medium energy antiproton program (HESR) . The accumulation rings will be used for antiprotons and ion running. Below is a comparison of possible medium energy programs for what Fermilab has achieved and the design of GSI FAIR. Beam Profiles Most precise measurement of the ψ(2S) width despite much smaller statistics than e+e- E760 & E835 PRECISION Resonance parameters can be determined from interference between a continuum process and the resonance. The continuum “amplifies” the resonance E835 example in 4 photons pp c0  , /, π0π0 Should expand interference analyses to more channels; in particular pp at 90o 110 <68 [1012] Δp/p [10-5] AP50 Experiment Area Antiproton Physics Experiments PRECISION