Spin dependence in high pT2p^{2}_{T} elastic pp and np scattering

Using the polarized proton capability of the Argonne ZGS the authors recently made 90 degrees /sub cm/ measurements of elastic pp scattering from 6 to 11.75 GeV/c, determining the parallel and anti- parallel pure initial spin state cross sections and the associated spin-spin parameter A/sub nn/ with the spins normal to the scattering plane. They find that the parallel to anti-parallel cross section ratio rises dramatically from 1.2+or-.06 at p/sub t//sup 2/=3.3 (GeV /c)/sup 2/ to 3.2+or-.4 at 4.8 (GeV/c)/sup 2/, similar to the p/sub T //sup 2/ dependence previously observed at the fixed laboratory momentum of 11.75 GeV/c. They have also extended the measurements at 6 GeV/c and find that A/sub nn/ has a small but sharp rise at 90 degrees /sub cm/. In addition a month of 12 GeV/c polarized deuteron acceleration in the ZGS enabled them to measure two A/sub nn/ at two points at 6 GeV/c for np elastic scattering: A/sub nn/=-.17+or-.04 at p/sub T//sup 2/=.8, A/sub nn/=-.19+or-.05 at P/sub T//sup 2/=1.0. These values are opposite in sign from the pp results at the same momentum. (4 refs)

Q2Q^2 Independence of QF2/F1QF_2/F_1, Poincare Invariance and the Non-Conservation of Helicity

A relativistic constituent quark model is found to reproduce the recent data regarding the ratio of proton form factors, $F_2(Q^2)/F_1(Q^2)$. We show that imposing Poincare invariance leads to substantial violation of the helicity conservation rule, as well as an analytic result that the ratio $F_2(Q^2)/F_1(Q^2)\sim 1/Q$ for intermediate values of $Q^2$.Comment: 13 pages, 7 figures, to be submitted to Phys. Rev. C typos corrected, references added, 1 new figure to show very high Q^2 behavio

Risk-reducing hysterectomy and bilateral salpingo-oophorectomy in female heterozygotes of pathogenic mismatch repair variants: a Prospective Lynch Syndrome Database report

Purpose To determine impact of risk-reducing hysterectomy and bilateral salpingo-oophorectomy (BSO) on gynecological cancer incidence and death in heterozygotes of pathogenic MMR (path_MMR) variants. Methods The Prospective Lynch Syndrome Database was used to investigate the effects of gynecological risk-reducing surgery (RRS) at different ages. Results Risk-reducing hysterectomy at 25 years of age prevents endometrial cancer before 50 years in 15%, 18%, 13%, and 0% of path_MLH1, path_MSH2, path_MSH6, and path_PMS2 heterozygotes and death in 2%, 2%, 1%, and 0%, respectively. Risk-reducing BSO at 25 years of age prevents ovarian cancer before 50 years in 6%, 11%, 2%, and 0% and death in 1%, 2%, 0%, and 0%, respectively. Risk-reducing hysterectomy at 40 years prevents endometrial cancer by 50 years in 13%, 16%, 11%, and 0% and death in 1%, 2%, 1%, and 0%, respectively. BSO at 40 years prevents ovarian cancer before 50 years in 4%, 8%, 0%, and 0%, and death in 1%, 1%, 0%, and 0%, respectively. Conclusion Little benefit is gained by performing RRS before 40 years of age and premenopausal BSO in path_MSH6 and path_PMS2 heterozygotes has no measurable benefit for mortality. These findings may aid decision making for women with LS who are considering RRS.Hereditary cancer genetic

Effect of synchrotron radiation in the proposed 4 GeV Argonne microtron

Synchrotron radiation in the sector magnets of the 4-GeV microtron designed at the Argonne National Laboratory produces a small but noticeable distortion of the closed orbits of the system and a very-significant growth of the horizontal and longitudinal phase-space emittances. Because of the small apertures in the three 25-meter linacs, it is important that the expected growth of the beam be calculated as accurately as possible. For this reason, a computer program has been written which follows the motions of individual electrons in the four dimensional horizontal and longitudinal phase space as they are accelerated in the system. As the electrons go through the sector magnets, they emit quanta at random with randomly chosen energies. The final results show 63% emittance (area ..pi..) values of 0.15 mm mrad and 630 keV degrees for the horizontal and longitudinal phase spaces, respectively. The 99% values are about 4.6 times larger

Revised lattice for the APS storage ring

As a result of more detailed engineering studies of vacuum chamber components and related accelerator physics studies, the circumference of the APS storage ring is increased by 44 m to a value of 1104 m. The increase is 1.1 m for each of the 40 sectors. The insertion region straight section is lengthened by 0.52 m to 6.72 m. This allows full 20-cm vacuum chamber transition sections leading into and out of the 5.2-m insertion devices. Computer studies using TBCI and MAFIA-T3 have indicated that 20-cm-long transition regions reduce the transverse coupling impedance to an Acceptable low value. The results for 10-cm transition length were marginal

The positron accumulator ring for the APS

The Positron Accumulator Ring (PAR) is designed to accumulate and damp positrons from the 450-MeV linac during the 0.5-s cycle time of the injector synchrotron for the APS 7-GeV storage ring. During 0.4 s of each synchrotron cycle, up to 24 linac pulses are injected into the horizontal phase space of the PAR at a 60-Hz rate. Each injected pulse occupies about 1.3 of the circumference of the accumulator ring. After 0.1 s for longitudinal damping, the single accumulated bunch is transferred to one of the 353-MHz buckets of the injector synchrotron RF system. The bunch is accelerated to 7 GeV and transferred to the storage ring, while the PAR accumulates the next bunch of positrons. 2 refs., 3 figs., 2 tabs

A positron accumulator ring for APS

The new positron injection scheme is as follows. The cycle rate of the injector synchrotron is increased to 2 Hz. During 0.4 sec of each 0.5-sec synchrotron cycle, 24 linac pulses are injected into the horizontal phase space of the PAR at a 60-Hz rate. Each injected pulse occupies about 1/3 of the circumference of the accumulator ring. After 0.1 sec for longitudinal damping, the single accumulated bunch is transferred into one of the 352.96-MHz buckets of the injector synchrotron RF system. This single bunch is accelerated to 7 GeV and transferred into the storage ring while the PAR accumulates the next bunch of positrons. The injector synchrotron requires only the one high-frequency RF system

Theoretical estimation of the dynamic aperture for a Chasman-Green lattice

A comparison between the predicted stability region and the results of tracking for the 7-GeV Advanced Photon Source CDR lattice is given. The tracking results are obtained by searching for the limit of stability in N{sub y} for a fixed value for N{sub x}. (Negative N{sub x} is understood to mean cos {phi}{sub xo} = {minus}1.) The limits of the stable region for this lattice are caused by the chromaticity correcting sextupoles and the predominance of the integral resonance for v{sub x} = 0.88 per period

Lattice considerations for a tau-charm factory

The magnet lattice appropriate for a tau-charm factory had been studied extensively. Here we discuss two possible simplifying features which make the design, construction, and operation of the machine simpler without sacrificing performance. These two features may be characterized and identified as (a) luminosity optimization in the ``monochromatic`` mode, and (b) chromaticity correction with sextupoles only in the arcs

Preliminary study of insertion device effect on dynamic aperture using RACETRACK

We studied the effects of an insertion device (ID) on the dynamic aperture using the new version of RACETRACK. We found that the nonlinear effect of the ID is the dominant effect on the dynamic aperture reduction compared to the other multipole errors which exist in the otherwise ideal lattice. The previous study of dynamic aperture was based on the assumption that the effect of the fast oscillating terms in L. Smith`s Hamiltonian is small, and hence can be neglected in the simulation. The remarkable agreement between the previous study and the current results using RACETRACK, including all effects of the fast oscillating terms, justified those assumptions at least for the APS ring