Microwave Schottky diagnostic systems for the Fermilab Tevatron, Recycler, and CERN LHC

A means for non-invasive measurement of transverse and longitudinal characteristics of bunched beams in synchrotrons has been developed based on high sensitivity slotted waveguide pickups. The pickups allow for bandwidths exceeding hundreds of MHz while maintaining good beam sensitivity characteristics. Wide bandwidth is essential to allow bunch-by-bunch measurements by means of a fast gate. The Schottky detector system is installed and successfully commissioned in the Fermilab Tevatron, Recycler and CERN LHC synchrotrons. Measurement capabilities include tune, chromaticity, and momentum spread of single or multiple beam bunches in any combination. With appropriate calibrations, emittance can also be measured by integrating the area under the incoherent tune sidebands

Signal to Noise and Dynamic Range Issues in System Design

Abstract Study of signal to noise and dynamic range of systems is a very important part of engineering. The topic of signal to noise has been covered extensively in the literature, but not necessarily from a practical standpoint. Discussion of dynamic range issues is virtually missing from most fundamental texts. This paper will attempt to present practical ways of looking at system design. For completeness, the fundamental equations will be included, but the emphasis will be on real system implementation. The paper will draw extensively from actual system designs at Fermilab

LARP LHC 4.8 GHZ Schottky System Initial Commissioning with Beam

The LHC Schottky system consists for four independent 4.8 GHz triple down conversion receivers with associated data acquisition systems. Each system is capable of measuring tune, chromaticity, momentum spread in either horizontal or vertical planes; two systems per beam. The hardware commissioning has taken place from spring through fall of 2010. With nominal bunch beam currents of 1011 protons, the first incoherent Schottky signals were detected and analyzed. This paper will report on these initial commissioning results. A companion paper will report on the data analysis curve fitting and remote control user interface of the system.Comment: 3 pp. Particle Accelerator, 24th Conference (PAC'11) 2011. 28 Mar - 1 Apr 2011. New York, US

Progress in Antiproton Production at the Fermilab Tevatron Collider

Fermilab Collider Run II has been ongoing since 2001. During this time peak luminosities in the Tevatron have increased from approximately 10 x 10{sup 30} cm{sup -2}sec{sup -1} to 300 x 10{sup 30} cm{sup 02}sec{sup -1}. A major contributing factor in this remarkable performance is a greatly improved antiproton production capability. Since the beginning of Run II, the average antiproton accumulation rate has increased from 2 x 10{sup 10}{anti p}/hr to about 24 x 10{sup 10}{anti p}/hr. Peak antiproton stacking rates presently exceed 28 x 10{sup 10}{anti p}/hr. The antiproton stacking rate has nearly doubled since 2005. It is this recent progress that is the focus of this paper. The process of transferring antiprotons to the Recycler Ring for subsequent transfer to the collider has been significantly restructured and streamlined, yielding additional cycle time for antiproton production. Improvements to the target station have greatly increased the antiproton yield from the production target. The performance of the Antiproton Source stochastic cooling systems has been enhanced by upgrades to the cooling electronics, accelerator lattice optimization, and improved operating procedures. In this paper, we will briefly report on each of these modifications

Noise Performance of the Debuncher Stchastic Cooling Systems

A careful measurement of the system noise performance for all 12 Debuncher stochastic cooling systems has been performed. The opportunity to make the measurement was due to a pickup tank warm up to fix a bad preamplifier. A HP power meter and spectrum analyzer were used to measure the noise power and spectral characteristics of each system. Signals were monitored in the tunnel at the medium level transfer switch, before any variable gain devices. Noise power levels observed ranged between -10 to -30 dBm, which is well within the linear calibration range of the power meter. The noise floor of the power meter was measured to be below -40 dBm. The temperature of the tunnel for the warm measurements was 80 degrees F or 300 Kelvin. The tanks had been at tunnel temperature for weeks when the warm measurement was made. There was no vacuum in the tanks for the warm measurement. The cold temperature of the tanks at liquid helium was 4.5-5 K. 5K was used in the calculations. No component changes were made between the measurements. The gain of the cryogenic amplifier increases with a decrease in operating temperature. The gain of the cryo amplifier was carefully measured both warm and cold so that this change could be taken into account. The Noise Figure in dB and effective noise temperature are derived from the equations below. T2-T1 is the difference in operation temperature in degrees Kelvin, in this case 300-5 or 295 deg. K. Y is the excess noise ratio, which is measured in dB by the power meter by taking the difference in noise power between warm and cold measurements. This log value must be converted to linear for use in this equation. The value for Y is also corrected for the increase in gain due to the change in the operating temperature of the amplifier. This data was derived from the warm and cold preamp temperatures measured in the tunnel. The noise figure NF used in the effective noise temperature equation must also be converted to linear. Except for two systems where noise was measured to be below reasonable levels (in red on spreadsheet), the numbers appear to be reasonable

ARF1 Frequency and Amplitude Curve Calibration

ARF1 was calibrated and checked on 4/18/01. The technique used was to set the start/stop timers (A:R1LLT1 and A:R1LLT2) for duration of 200 msec. Driving the cavities for longer than 200 msec at full voltage could put some stress on the Hipotronics anode supply. The Camac curve generator card was substituted with a precision DC voltage source. Data for both amplitude and frequency were taken with the DC source. A HP 8563A spectrum analyzer in zero span with resolution bandwidth of 1 MHz at a center frequency of 52.818 MHz was used to take the amplitude data. The dynamic curve was a triangle waveform provided by a triggered HP3213A function generator. Frequency was measured on the Fluke frequency counter mounted in the rack in AP50 (with the high level RF off). The attached data and graph contain the current calibration. ARF1-1 is slightly lower voltage than ARF1-2, but well within spec. The calibration was made with the Anode supply at 9 Kvolts, the bend busses were off due to an access that was in progress. Due to the unregulated Anode supply, the voltage levels observed may be slightly higher than with bend busses on. The dynamic performance with the triangle waveform looks correct. The peak voltages measured for ARF1-1 and ARF1-2 were 27.1 KV and 32.9 KV respectively. The calibration for the fanback is 22 Kvolts per volt for ARF1-1&2, and 66 Kvolts per volt for ARF1 Sum. ARF1 has historically run with a flat top voltage duration of 160 msec. The current curve generator has lengthened that time considerably. The curve generator should take full advantage of the 65 dB dynamic range measured

Debuncher Momentum Cooling Systems Signal to Noise Measurements

The Debuncher Momentum cooling systems were carefully measured for signal to noise. It was observed that cooling performance was not optimum. Closer inspection shows that the installed front-end bandpass filters are wider than the pickup response. (The original filters were specified to be wider so that none of the available bandwidth would be clipped.) The end result is excess noise is amplified and passed onto the kickers unimpeded, hence, reducing the achievable system gain. From this data, new filters should be designed to improve performance. New system bandwidths are specified on the data figures. Also included are the transfer function measurements that clearly show adjacent band response. In band 4 upper, the adjacent lobes are strong and out of phase. This is also degrading the system performance. The correlation between spectrum analyzer signal to noise and network analyzer system transfer functions is very strong. The table below has a calculation of expected improvement of front noise reduction by means of building new front-end bandpass filters. The calculation is based on a flat input noise spectrum and is a linear estimation of improvement. The listed 3dB bandwidths of the original filters are from measured data. The expected bandwidth is taken from the linear spectrum analyzer plots and is closer to a 10 dB bandwidth making the percentage improvement conservative. The signal to noise measurements are taken with circulating pbars in the Debuncher. One cooling system was measured at a time with all others off. Beam currents are below ten microamperes

Performance of the Upgraded Stacktail Momentum Cooling System in the Fermilab Antiproton Source

Major changes in the Stacktail Momentum Stochastic Cooling system have resulted in an improved stacking rate as well as the capability to stack larger quantities of antiprotons. Both these effects result in higher initial and integrated luminosity for colliding beam physics. An overview of the changes and actual system performance is presented

Diagnostics summary: Working group T9

The diagnostics T9 group was charged with reviewing the diagnostic requirements of the proposed accelerators for the future. The list includes the e+e- colliders, Muon Neutrino source, NLC, Proton Driver, Tesla, and the VLHC. While the machines vary widely on diagnostic requirements, there are many similarities that were discovered. The following sections will attempt to point out the similarities and requirements for R and D for these future accelerators. To answer the Charge to the group they organized joint sessions with most of the machine groups and several of the technical groups. In addition, due to their overwhelming importance, they held a special session on position monitor systems. For each of the joint machine group sessions they generated a table of required diagnostic systems, selected the highest priority items using a ranking based on need and RD effort, and pondered a RD path leading from the present state of the technology to a system satisfying the requirement. They used the joint technical group sessions to collect up to date RD plans and to assess the applicability of new ideas in a broad range of topics. As required by their Charge, they have also tried to include promising new ideas