Summary of Fermilab's Recycler Electron Cooler Operation and Studies

Fermilab's Recycler ring was used as a storage ring for accumulation and subsequent manipulations of 8-GeV antiprotons destined for the Tevatron collider. To satisfy these missions, a unique electron cooling system was designed, developed and successfully implemented. The most important features that distinguish the Recycler cooler from other existing electron coolers are its relativistic energy (it employs a 4.3 MeV, 0.1 A DC electron beam), a weak continuous longitudinal magnetic field in the cooling section (~100 G), and lumped focusing elsewhere. With the termination of the collider operation at Fermilab, the cooler operation was also terminated. In this article, we will summarize the experience of commissioning, optimizing and running this unique machine over the 6 years of its existence.Comment: 3 pp. 3rd International Particle Accelerator Conference (IPAC 2012) 20-25 May 2012. New Orleans, Louisian

The State of the Art in Hadron Beam Cooling

Cooling of hadron beams (including heavy-ions) is a powerful technique by which accelerator facilities around the world achieve the necessary beam brightness for their physics research. In this paper, we will give an overview of the latest developments in hadron beam cooling, for which high energy electron cooling at Fermilab's Recycler ring and bunched beam stochastic cooling at Brookhaven National Laboratory's RHIC facility represent two recent major accomplishments. Novel ideas in the field will also be introduced.Comment: 7 pages, 7 figures, ICFA-HB2008 Invited presentatio

Deficiency of G1 regulators P53, P21Cip1 and/or pRb decreases hepatocyte sensitivity to TGFbeta cell cycle arrest

TGFbeta is critical to control hepatocyte proliferation by inducing G1-growth arrest through multiple pathways leading to inhibition of E2F transcription activity. The retinoblastoma protein pRb is a key controller of E2F activity and G1/S transition which can be inhibited in viral hepatitis. It is not known whether the impairment of pRb would alter the growth inhibitory potential of TGFbeta in disease. We asked how Rb-deficiency would affect responses to TGFbeta-induced cell cycle arrest.Publisher PDFPeer reviewe

Modélisation de l'hydrodynamique d'un décanteur primaire de station d'épuration

Les qualités de fonctionnement d'un décanteur primaire de station d'épuration d'eaux usées dépendent essentiellement de ses caractéristiques hydrauliques. Le but de ce travail est la caractérisation et la modélisation de l'hydrodynamique d'un décanteur réel d'une station d'épuration d'eaux usées urbaines.Cette opération s'effectue par la détermination de la Distribution des Temps de Séjour (DTS) de la phase liquide du décanteur par traçage au chlorure de lithium. Simultanément, les évolutions des débits d'effluent à traiter et des rendements d'épuration en Matières En Suspension (MES) ont été suivis.La courbe de DTS obtenue a permis une modélisation de l'hydrodynamique du décanteur primaire par des associations en série ou en parallèle de Réacteurs Parfaitement Agités (RPA). Le modèle hydrodynamique proposé, dont les résultats sont en très bonne concordanoe avec les résultats expérimentaux, est composé de 2 branches associées en parallèle: l'une traversée par une fraction a = 0,14 d'effluent entrant dans le décanteur est une cascade de 7 RPA d'un volume total de 77 m3. L'autre branche traversée par la fraction de débit restante (l-a) est composée de 2 modules en série: le premier module, caractérisant une zone de recirculation, est un RPA de 645 m3 en échange avec un second RPA de 1935 m3, la fraction de débit ß échangée est de 28. Le deuxième module de cette branche, représentant un écoulement uniforme, est une cascade de 7 RPA d'un volume total de 1 183 m3.Ce modèle hydrodynamique permet d'analyser les résultats obtenus quant à l'évolution des rendements d'épuration en MES mesurés dans le décanteur.The operating performances of wastewater treatment plant primary clarifiers essentially depend on hydraulic conditions. The aim of this paper is to characterize and to simulate the hydraulic flow regime of an existing sedimentaton tank.This study was carried out on a wastewater treatment plant primary clarifier. It is a circular clarifier of 3900 m3 in volume, 42 m in diameter, 2.1 m in straight useful height, and, 2.1m in height for the conical part. The inlet flow rate is between 1400 and 2700 m3/h, whereas the sequental (3 primary clarifiers) sludge extraction flow rate is about 20 m3/h.To characterize the liquid phase residence time distribution (RTD) in the clarifier, we did a tracing operation (pulse injection) with lithium chloride as tracer (20 kg of lithium chloride dissolved in 120 litres of tap-water). After the tracer injection, the lithium concentration at the outlet of the clarifier was measured as a function of time. During this experiment we also followed the evolution of inlet flow rates and the suspended solid (SS) retention efliciency ofthe clarifier. For 350 min of experimental time, the recuperation of lithium was 92.7%.The experimental RTD curve allowed us to develop a model for the primary clarifier hydrodynarnics by association of elementary units (completely stirred reactors, CSTR) in series or in parallel. The transfer function in the LAPLACE domain, G (s), and the mathematical expressions of the first order and second central order moments were determined for this model. The nurnerical simulation of RTD between the inlet and the outlet of the system was performed with the help of a general computer code which numerically calculates the RTD, using Fast Fourier Trandormation techniques, from a given transfer fucnction.The hydrodynamic model proposed in this study matches very well with the experimental results. It comprises two trranches associated in parallel. The first one, which is drived by an effluent flow rate fraction α (α=0,14), is treated as 7 CSTR's in series of 77 m3 in total volume. The second branch, which is drived by the remaining eflluent flow rate fraction (1-α), is composed of two modules associated in series. The first module, which characterizes a recycling zone, is treated as a CSTR of 645 m3 in volume exchanging with a second CSTR of 1935 m3 in volume, the exchanged flow rate fraction, ß, being equal to 28. The second module of this branch. which characterize a uniform flow zone, is represented by 7 CSTR's in series of 1183 m3 in total volume.These results are confirmed by the comparison of the first order and the second central order moments. Indeed, between t = 0 and t = 350 min., we find for the experimental curve µ1=l27 min and µ2=6957, and, for the proposed hydrodynamic model curve µ1=129 min and µ2=7154 which are equivalent values. Finally, the proposed hydrodynamic model makes possible the analysis of the primary clarifier performance with respect to suspended solid removal

Transverse instability of the antiproton beam in the Recycler Ring

The brightness of the antiproton beam in Fermilab's 8 GeV Recycler ring is limited by a transverse instability. This instability has occurred during the extraction process to the Tevatron for large stacks of antiprotons even with dampers in operation. This paper describes observed features of the instability, introduces the threshold phase density to characterize the beam stability, and finds the results to be in agreement with a resistive wall instability model. Effective exclusion of the longitudinal tails from Landau damping by decreasing the depth of the RF potential well is observed to lower the threshold density by up to a factor of two.Comment: 3 pp. Particle Accelerator, 24th Conference (PAC'11) 2011. 28 Mar - 1 Apr 2011. New York, US