The reaction n C{e,e'p) in the dip region (o> = 200 MeV, q = 400 MeV/c) has been measured in parallel kinematics for missing energies up to 160 MeV. A coincidence yield considerably larger than that expected for a one-body reaction process is observed, though the one-body contribution from p-and s-shell knockout is also present. A uniform continuum strength extends from beyond the p shell to the highest measured missing energies. This continuum strength is the dominant contribution to the (e,e f p) reaction process in the dip region.PACS numbers: 25.30.Fj

The dedicated murine PET (MuPET) scanner is a high-resolution, high-sensitivity, and low-cost preclinical PET camera designed and manufactured at our laboratory. In this article, we report its performance according to the NU 4-2008 standards of the National Electrical Manufacturers Association (NEMA). We also report the results of additional phantom and mouse studies. Methods: The MuPET scanner, which is integrated with a CT camera, is based on the photomultiplier-quadrant-sharing concept and comprises 180 blocks of 13 · 13 lutetium yttrium oxyorthosilicate crystals (1.24 · 1.4 · 9.5 mm 3 ) and 210 low-cost 19-mm photomultipliers. The camera has 78 detector rings, with an 11.6-cm axial field of view and a ring diameter of 16.6 cm. We measured the energy resolution, scatter fraction, sensitivity, spatial resolution, and counting rate performance of the scanner. In addition, we scanned the NEMA image-quality phantom, Micro Deluxe and Ultra-Micro Hot Spot phantoms, and 2 healthy mice. Results: The system average energy resolution was 14% at 511 keV. The average spatial resolution at the center of the field of view was about 1.2 mm, improving to 0.8 mm and remaining below 1.2 mm in the central 6-cm field of view when a resolution-recovery method was used. The absolute sensitivity of the camera was 6.38% for an energy window of 350-650 keV and a coincidence timing window of 3.4 ns. The system scatter fraction was 11.9% for the NEMA mouselike phantom and 28% for the ratlike phantom. The maximum noise-equivalent counting rate was 1,100 at 57 MBq for the mouselike phantom and 352 kcps at 65 MBq for the ratlike phantom. The 1-mm fillable rod was clearly observable using the NEMA image-quality phantom. The images of the Ultra-Micro Hot Spot phantom also showed the 1-mm hot rods. In the mouse studies, both the left and right ventricle walls were clearly observable, as were the Harderian glands. Conclusion: The MuPET camera has excellent resolution, sensitivity, counting rate, and imaging performance. The data show it is a powerful scanner for preclinical animal study and pharmaceutical development. Smal l-animal PET has been widely used in a broad range of applications in the field of biology and pharmaceutical development (1). Because of the small physical dimensions of rodents, achieving spatial resolution and detection sensitivity adequate to study small structures and the low concentration of receptors is challenging. In addition, to make the in vivo molecular imaging capability of PET accessible to more biology and genetics laboratories, thus facilitating the integration of biologic research and clinical medicine, lower camera-production costs are also needed.A preclinical dedicated murine PET (MuPET) camera has been designed and constructed at the University of Texas M.D. Anderson Cancer Center (2). It has been integrated with a CT camera into a compact gantry. The MuPET camera combines the advantages of a lower production cost with high resolution and high sensitivity. In this work, we report on the scanner's perfor...

No abstract

No abstract

No abstract

The ' C(e, e'p) reaction at the delta resonance has been measured for protons detected parallel to the momentum transfer at two kinematical situations: at the maximum and the low-energy-loss side of the peak. The cross section was measured for missing energies up to 320 and 220 MeV, respectively. In the missing energy spectrum two distinct structures are observed, which correspond to multinucleon knockout and quasifree pion production processes. In addition, there is a remnant of the quasifree knockout process.

We measured the 12 C(e,e ′ p) cross section as a function of missing energy in parallel kinematics for (q, ω) = (970 MeV/c, 330 MeV) and (990 MeV/c, 475 MeV). At ω = 475 MeV, at the maximum of the quasielastic peak, there is a large continuum (Em > 50 MeV) cross section extending out to the deepest missing energy measured, amounting to almost 50% of the measured cross section. The ratio of data to DWIA calculation is 0.4 for both the p-and s-shells. At ω = 330 MeV, well below the maximum of the quasielastic peak, the continuum cross section is much smaller and the ratio of data to DWIA calculation is 0.85 for the p-shell and 1.0 for the s-shell. We infer that one or more mechanisms that increase with ω transform some of the single-nucleon-knockout into multinucleon knockout, decreasing the valence knockout cross section and increasing the continuum cross section.

No abstract