70 research outputs found
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Polarization at the SLC
No full textThe Stanford Linear collider was designed to accommodate polarized electron beams. Longitudinally polarized electrons colliding with unpolarized positrons at a center of mass energy near the Z/sup 0/ mass can be used as novel and sensitive probes of the electroweak process. A gallium arsenide based photon emission source will provide a beam of longitudinally polarized electrons of about 45 percent polarization. A system of bend magnets and a superconducting solenoid will be used to rotate the spins so that the polarization is preserved while the 1.21 GeV electrons are stored in the damping ring. Another set of bend magnets and two superconducting solenoids orient the spin vectors so that longitudinal polarization of the electrons is achieved at the collision point with the unpolarized positrons. A system to monitor the polarization based on Moller and Compton scattering will be used. Nearly all major components have been fabricated and tested. Subsystems of the source and polarimeters have been installed, and studies are in progress. The installation and commissioning of the entire system will take place during available machine shutdown periods as the commissioning of SLC progresses. 8 refs., 16 figs., 1 tab
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Status of the SLC
No full textThe goals of the SLAC Linear Collider, SLC, are to develop the techniques of linear colliders and to do physics at and slightly above the energy necessary to produce the Z/sup 0/. A short review is given of the physics goals of the SLC, followed by the status of the SLC and its detectors. Plans for accelerating polarized electrons at SLC are also discussed. 6 figs. (LEW
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Experimental test of exchange degeneracy in hypercharge exchange reactions. [Helicity-flip and nonflip amplitudes, angular distribution, quark model]
No full textTwo pairs of line-reversed reactions ..pi../sup +/P ..-->.. K/sup +/..sigma../sup +/, K/sup -/p ..-->.. ..pi../sup -/..sigma../sup +/ and ..pi../sup +/p ..-->.. K/sup +/Y*/sup +/(1385), K/sup -/p ..-->.. ..pi../sup -/Y*/sup +/(1385) provide an experimental test of exchange degeneracy in hypercharge exchange reactions. From their study it is concluded that in contrast to the lower energy data, the 11.5 results for the two pairs of reactions are consistent with exchange degeneracy predictions for both helicity-flip and nonflip amplitudes. The Y(1385) decay angular distributions indicate that the quark model and Stodolsky--Sakurai predictions are in agreement with the main features of the data. However, small violations are observed at small momentum transfer. While the Y(1385) vertex is helicity-flip dominated, the nonvanishing of T/sub 3/2 - 1/2/ and T/sub -3/2 1/2/ suggests some finite helicity nonflip contribution in the forward direction. 23 references. (JFP
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Status of the SLC (SLAC Linear Collider)
No full textA short review of the physics goals and the status of the SLC is followed by a discussion of the energy spectrometer with center-of-mass energy resolution on a pulse-to-pulse basis of +-50 MeV/c/sup 2/. The status of the SLC polarization experiment is discussed. The expected physics program of the Mark II is given
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Polarized electron beams at SLAC
No full textSLAC has successfully accelerated high energy polarized electrons for the Stanford Linear Collider and fixed polarized nuclear target experiments. The polarized electron beams at SLAC use a gallium arsenide (GaAlAs for E-142) photon emission source to provide the beam of polarized electrons with polarization of approximately 28% (41% for E-142). While the beam emittance is reduced in the damping ring for SLC operation a system of bend magnets and superconducting solenoids preserve and orient the spin direction for maximum longitudinal polarization at the collision point. The electron polarization is monitored with a Compton scattering polarimeter, and was typically 22% at the e[plus]e[minus] collision point for the 1992 run. Improvements are discussed to increase the source polarization and to reduce the depolarization effects between the source and the collision point
Design of a high yield position source
No full textThe Stanford Linear Collider (SLC) requires a positron source with a yield large enough to give equal number of positrons and electrons at the interaction point. In addition, the colliding positrons must have an emittance and bunch length similar to the electron beam. This report describes the design of a high yield positron source to give these characteristics
Confirmation of exchange-degeneracy predictions in the line-reversed reactions: (1385) and (1385) at 11.5 GeV/c
No full textPolarimeters and Energy Spectrometers for the ILC Beam Delivery System
No full textThis article gives an overview of current plans and issues for polarimeters and energy spectrometers in the Beam Delivery System of the ILC. It is meant to serve as a useful reference for the Detector Letter of Intent documents currently being prepared. Concepts for high precision polarization and energy measurements exist. These concepts have resulted in detailed system layouts that are included in the RDR description for the Beam Delivery System. The RDR includes both upstream and downstream polarimeters and energy spectrometers for both beams. This provides needed complementarity and redundancy for achieving the precision required, with adequate control and demonstration of systematic errors. The BDS polarimeters and energy spectrometers need to be a joint effort of the ILC BDS team and the Detector collaborations, with collaboration members responsible for the performance and accuracy of the measurements. Details for this collaboration and assigning of responsibilities remain to be worked out. There is also a demonstrated need for Detector physicists to play an active role in the design and evaluation of accelerator components that impact beam polarization and beam energy capabilities, including the polarized source and spin rotator systems. A workshop was held in 2008 on ILC Polarization and Energy measurements, which resulted in a set of recommendations for the ILC design and operation. Additional input and action is needed on these from the Detector collaborations, the Research Director and the GDE. Work is continuing during the ILC engineering design phase to further optimize the polarimeter and energy spectrometer concepts and fully implement them in the ILC. This includes consideration for alternative methods, detailed design and cost estimates, and prototype and test beam activities
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