CBETA: First Multipass Superconducting Linear Accelerator with Energy Recovery.

Energy recovery has been achieved in a multipass linear accelerator, demonstrating a technology for more compact particle accelerators operating at higher currents and reduced energy consumption. Energy delivered to the beam during the first four passes through the accelerating structure was recovered during four subsequent decelerating passes. High-energy efficiency was achieved by the use of superconducting accelerating cavities and permanent magnets. The fixed-field alternating-gradient optical system used for the return loop successfully transported electron bunches of 42, 78, 114, and 150 MeV in a common vacuum chamber. This new kind of accelerator, an eight-pass energy recovery linac, has the potential to accelerate much higher current than existing linear accelerators while maintaining small beam dimensions and consuming much less energy per electron.

Measurement of the Spin Tune Using the Coherent Spin Motion of Polarized Protons in a Storage Ring.

This Letter reports the first spin tune measurement at high energies (24 and 255 GeV) with a driven coherent spin motion. To maintain polarization in a polarized proton collider, it is important to know the spin tune of the polarized proton beam, which is defined as the number of full spin precessions per revolution. A nine-magnet spin flipper has demonstrated high spin-flip efficiency in the presence of two Siberian snakes [H. Huang et al., Phys. Rev. Lett. 120, 264804 (2018).10.1103/PhysRevLett.120.264804]. The spin flipper drives a spin resonance with a given frequency (or tune) and strength. When the drive tune is close to the spin tune, the proton spin direction is not vertical anymore, but precesses around the vertical direction. By measuring the precession frequency of the horizontal component, the spin tune can be precisely measured. A driven coherent spin motion and fast turn-by-turn polarization measurement are keys to the measurement. The vertical spin direction is restored after turning the spin flipper off and the polarization value is not affected by the measurement. The fact that this manipulation preserves the polarization makes it possible to measure the spin tune during the operation of a high energy accelerator.

High Spin-Flip Efficiency at 255 GeV for Polarized Protons in a Ring With Two Full Siberian Snakes.

In polarized proton collision experiments, it is highly advantageous to flip the spin of each bunch of protons during the stores to reduce the systematic errors. Experiments done at energies less than 2 GeV have demonstrated a spin-flip efficiency over 99%. At high energy colliders with Siberian snakes, a single magnet spin flipper does not work because of the large spin tune spread and the generation of multiple, overlapping resonances. A more sophisticated spin flipper, constructed of nine-dipole magnets, was used to flip the spin in the BNL Relativistic Heavy Ion Collider. A special optics choice was also used to make the spin tune spread very small. A 97% spin-flip efficiency was measured at both 24 and 255 GeV. These results show that efficient spin flipping can be achieved at high energies using a nine-magnet spin flipper.

A storage ring experiment to detect a proton electric dipole moment.

A new experiment is described to detect a permanent electric dipole moment of the proton with a sensitivity of 10-29 e ⋅ cm by using polarized "magic" momentum 0.7 GeV/c protons in an all-electric storage ring. Systematic errors relevant to the experiment are discussed and techniques to address them are presented. The measurement is sensitive to new physics beyond the standard model at the scale of 3000 TeV.

Determination of parotid sulfate secretion in sheep by means of ultrasonic flow probes.

The bilateral output of sulfate in parotid saliva, the relationship with its plasma level and with parotid flow, and its variation according to feeding behavior were determined in ad libitum, normal-sulfate (0.28% DM)-fed sheep (n = 6) using a transit time ultrasonic flow meter system to measure salivary flow. Ultrasonic flow meter probes were bilaterally implanted, under general anesthesia, around parotid ducts previously fitted through their oral ends with nonobstructive sampling catheters. Salivary flows were continuously recorded during 24 h, and saliva and blood samples for sulfate determinations were obtained hourly. Jaw movements were monitored with the submandibular balloon technique. The sulfate concentration in parotid saliva (mean of the group = 4.9 +/- 3.7 microg/mL) showed high variability between sheep (individual means from 0.4 +/- 0.3 to 9.3 +/- 5.9 microg/mL) and averaged 12.3% of the more stable plasma level (41.2 +/- 8.1 microg/mL). Pronounced intraindividual variations were also evident (0.1 to 26.3 microg of sulphate/mL of parotid saliva), in strong association with the fluctuations of salivary output. In 4 sheep, a decreasing exponential relationship was observed between parotid sulfate concentration and salivary secretion rate (r2 = 0.36, P < 0.01). This fact and the absence of a relationship between sulfate levels in plasma and in saliva suggest a sulfate secretory process during the passage of primary saliva through the ductal tree of the gland. The greatest rates of bilateral salivary sulfate output were observed during feeding (14.1 +/- 14.0 microg/min) and rumination (12.7 +/- 11.0 microg/min). Nevertheless, 49% of the sulfate output in parotid saliva was present during rest, as a result of the length of the resting times. The contribution of parotid sulfate to the ruminal S pool was highly variable and averaged 13.2 mg/d, representing less than 1% of the S intake. In conclusion, the accurate, reliable, nonobstructive, and bilateral salivary flow monitoring, using a previously characterized ultrasonic flow meter technique, allowed a detailed determination of the secretory dynamics of sulfate in parotid saliva, without disturbing the animal's routine or altering the physiological regulation of salivary output. The results indicated that, in the absence of S deficiency, the recycling of sulfate via saliva seems not to be a major factor in sheep nutrition.

Determination of parotid urea secretion in sheep by means of ultrasonic flow probes and a multifactorial regression analysis.

For determination of the dynamics of parotid urea secretion in conscious sheep, a previously standardized transit time ultrasonic flow metering system was used to measure bilateral parotid flow. Six ewes fed for ad libitum consumption were prepared under halothane anesthesia with ultrasonic probes around both parotid ducts; these ducts were also cannulated orally. After probe encapsulation (8 d), parotid flows were recorded during 24 h, and samples of saliva and blood for urea determination were obtained hourly. Jaw movements were recorded by means of a submandibular balloon to monitor feeding behavior. Urea concentration in parotid saliva was 60 to 74% of that in plasma (a positive linear correlation existed) and was poorly influenced by the parotid flow. The amount of urea secreted with parotid saliva was directly related to the salivation rate. To calculate the urea secretion in parotid saliva, a multiple linear regression model was developed from computer-calculated parotid flows over 1-min periods and plasma urea concentration. The model was accurate because the plot of calculated vs measured values was not significantly different from the line of identity. The daily parotid urea N varied from .35 to 1.02 g among ewes. The higher urea secretion rate found during rumination and eating (1.32+/-.42 and .98 +/-.33 mg/min, respectively) vs. during rest (.60+/-.39 mg/ min, P<.05) was due to higher salivation rates (5.17 +/-1.46, 3.56+/-.90, and 2.04+/-.52 mL/min, respectively, P<.05) rather than to changes in saliva urea concentrations (saliva:plasma urea ratio = .65+/-.04, .67+/-.04, and .68+/-.03, respectively). Of the daily parotid urea output, 40.8% was secreted during rest. The contribution of parotid urea N to the ruminal N pool was relatively small (1.2 to 3.7% of the N intake, which was 23.0 to 33.6 g/d). These techniques allowed direct and precise measurements of parotid urea secretion without disturbing the animal or altering the physiological regulation of salivary secretion.

Comparative pharmacokinetics of sulfamethazine in plasma and parotid saliva of sheep.

Salivary output in sheep is large enough to be considered a physiologic body fluid compartment. The hypothesis for this work was that pharmacokinetics of sulfamethazine in saliva was similar to that in plasma. A reliable technique was developed to measure parotid salivary output. Mean output of saliva was 3.18 +/- 1.04 L from a single parotid gland per day with a mean flow of 2.21 +/- 0.43 mL/min. Using concentrations of sulfamethazine in parotid saliva made it possible to calculate the total passage of sulfamethazine to parotid saliva, which was calculated to be 3.5% of the total dose. Pharmacokinetic variables obtained for sulfamethazine in plasma and in saliva were closely related (AUC 1408 micrograms.h/mL and AUC 1484 micrograms.h/mL; Vdarea 0.434 L/kg and Vdarea 0.374 L/kg; t 1/2 beta 4.30 h and 3.46 h, respectively) and no substantial differences were observed. The convenience of using salivary concentrations of sulfamethazine for drug monitoring is discussed.

Parotid secretion daily patterns and measurement with ultrasonic flow probes in conscious sheep.

Five sheep under halothane anesthesia were prepared with bilateral transit time ultrasonic flow probes around the parotid ducts. The ducts were fitted with non-obstructive sampling catheters through their oral ends. After probe encapsulation (8 days), salivary flows were continuously recorded (4-5 days, dual-channel ultrasonic flowmeter). For rumination, eating, resting and drinking periods, respectively, the parotid daily outputs recorded were 1.96 +/- 0.57, 0.97 +/- 0.34, 2.84 +/- 0.41 and < 0.041 and bilateral flow rates were 6.76 +/- 0.70, 5.63 +/- 1.42, 2.50 +/- 0.58 and 1.69 +/- 0.88 ml min-1. An ipsilateral secretory reflex was evident when the sheep changed chewing side during rumination (4.44 +/- 0.96 ml min-1 ipsilateral vs 2.63 +/- 0.90 ml min-1 contralateral flow, P < 0.01). Secretory patterns are described in detail during rest, eating, drinking and rumination periods. The pH of parotid saliva (8.36 +/- 0.14) and the osmolality (273.8 +/- 9.9 mosmol kg-1) were independent of secretory rates. In situ probe calibration showed high accuracy (0-9%). The main advantages of the technique are its accuracy and good tolerance, duct integrity and maintenance of nervous supply, minimal surgery, uninterrupted salivary flow, simultaneous bilateral measurements and precise flow monitoring, permitting detailed observations.