摘要:

Single strained, medium‐doped (5×1018/cm3) GaAs photocathodes show the surface charge limit (SCL). The SCL poses a serious problem for operation of polarized electron sources at future linear colliders such as the NLC/JLC. A high‐gradient‐doping technique has been applied to address this problem. A 5 –7.5 nmp‐type surface layer doped to 5×1019/cm3is found sufficient to overcome the SCL, while maintaining high beam polarization. This technique can be employed to meet the charge requirements of the NLC with a polarization approaching 80&percent;. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1607301

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

This talks addresses the operation of the polarized source at the Mainz Microtron MAMI. The source is operating with selected photocathodes of modulation doped, uniaxially strained layer photocathodes, which results in an average spin polarization of 80&percent; and a quantum efficiency of typically 2 &mgr;A/mW. The operative lifetime has been improved by employing a novel activation technique which reduces transmission losses in the vicinity of the cathode. In addition a considerable simplification of the laser system has become possible by improving the power output of laser diode seed lasers so that it is not necessary to employ power amplifier units. It was shown that the potential for increasing the laser power is limited in our setup because of the thermal resistance between cathode and the surrounding electrode. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1607302

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

We present the design and experimental results for the flashlamp‐pumped Ti:Sapphire laser system used at the Stanford Linear Accelerator Center (SLAC). This laser system is used in conjunction with the Polarized Electron Source to generate polarized electron beams for fixed target experiments (e.g. the E‐158 experiment). The unique capabilities such as high pulse‐to‐pulse stability, long pulse length and high repetition rate is discussed. Emphasis is placed on recent modifications of the laser system, which allow ultra‐stable operation with 0.5&percent; rms intensity jitter. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1607303

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

During the fall of 2001, the polarized source at MIT delivered over 140 Coulombs of high quality polarized beams to the SAMPLE‐III 125 MeV parity violating experiment. Prior to the experiment, the source was reconfigured to deliver highly polarized beam using the new high power diode array laser system with large aperture beam optics, and a strained layer GaAsP photocathode from St. Petersburg. The results of these tests will be presented. The production run for SAMPLE‐III was then carried out with a bulk GaAs and the Ar‐Ti:Sapphire laser system. Since April of this year, the source has been delivering high polarization beams to the South Hall Ring for commissioning of the BLAST spectrometer. The stored current in the ring exceeds 100 mA. This is accomplished using the high power diode laser system and high‐gradient‐doped strained GaAsP photocathodes from Bandwidth Semiconductor Inc. tuned for 810 nm. The operational lifetime of the photocathode is excellent. A status report of the Bates polarized source and the operational experience of delivering high polarization beam to SHR will be presented. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1607304

出版商:AIP    

年代:1903

数据来源: AIP