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Abstract-The US LHC Accelerator Research Program (LARP)and CERN combined their efforts in developing Nb3Sn magnets for the High-Luminosity LHC upgrade. The ultimate goal of this collaboration is to fabricate large aperture Nb3Sn quadrupoles for the LHC interaction regions (IR). These magnets will replace the present 70 mm aperture NbTi quadrupole triplets for expected increase of the LHC peak luminosity by a factor of 5. Over the past decade LARP successfully fabricated and tested short and long models of 90 mm and 120 mm aperture Nb3Sn quadrupoles. Recently the first short model of 150 mm diameter quadrupole MQXFS was built with coils fabricated both by the LARP and CERN. The magnet performance was tested at Fermilab's vertical magnet test facility. This paper reports the test results, including the quench training at 1.9 K, ramp rate and temperature dependence studies. Index Terms-Accelerator magnets, large hadron collider, Nb3Sn coils, superconducting magnets

Abstrflct -High-gradient snpcrconducting quadiupole magnets me hcjng devcloped by thc US LIIC Accclcrsior Projca for thc Interaclion Rcgions of the Largc Hadron Collider. Dctcrininntion of the magnetic iixis lor alignmcnt of thcsc magnets will hc performed using n singlc stretcticd wire systcm. These incnsuremcnts will be dnne both a1 mom and cryogenic temperatures with very IOJI~ wire lenglhs, up to 20111. This paper repork on thc stretchcd wire alignmeiit tncthodology to be employed and thc resiilts of rccerit rontn-fciiipcraliire mc:isuretnents on n 2 m modcl magnci wiili long wirc lengths. INTROUUCTKIN'l'lic low-p insertion qnadrupoks currently under tlevelopmcnt at PNAL and KBK will have their alignment parameters metisurcd after being installed in cryostats at PNAL. As these magnets providc the final focus before collision for thc LHC beam, thclr alignment tnust be accurately determined. Such dignincnt measurements are required at both room and cryogenic temperatures because only thc FNAL magnets will undergo testing at cryogenic temperatures; thc remaining tnagncts will rcly on warm alignnicnt measu.cmcnts and measnreincnt of the correlation betwecn warm and cold alignment parameters. Purthermorc, although the length of thc MQX magnet assemblies rangc from 5.5 to 6.5 m, the Q2 has two such lnilgnets and a corrector package housed wiihin R singlc cryostat approximatcly 15 m in length. When mountcd on B tcst stand, with cryogcnic etid cans, aligiiment measurements inust be performed within ii beam tube o f length -20 m.The alignment device chosen for these tneasurcments is i\ SiIiglc Stretched Wire (SSW) systcm of the type used nt IlIiSY for thc HERA qiiadrripules [ I ] and for the Main Injector quadrupoles at PNAL [ 2 ] . Thc goals for rhe systcm arc tneasurcinent in the transvcrse planc of the average quadrupole axis (vertical and horizontal) to 50 ptn and roll to 100 p a d (including transfcr to magnct l'irlucials) under thc mcnsurement conditions cited abovc, hi additinn, in order to place the Q2AiQ2B device SO as to minimize thc eFFects of relative misalignments of the scparnte elcments (which cannot be adjusted after installation i o the cryostat), the true axcs of the individual Q2AlQZB magnets innst also be determined (ratlicr than just their average centers). This papcr outlines the syslem and techniqucs that will be used to achieve these measurement rcquiretnents and prcacnts the rcsults of recent tcsts o f thc methods involved.Manascripl rcccivcd Scptcinbcr 27. 1999. Work supportcd hy tlic U S . Dclurtnicnr uf Ewrgy.A single wirc is stretchcd between two sets r)f precision motion stages ils shown sclicmarically in Fig. 1. Thc return wire of the loop lics fixed on the bottom of the beam pipe or outside the magncr. Fig. I . Cnordinntc definitions fur SSW and inognel systcniThe vcctor potential at the ccnter of thc quadrupolc field of gradient ,p can bc expressed as where 11, b,,, a, arc thc multipole order, and normnl and skew coefficients, R is the rcference radius, x.y arc the huriiontal and verti...

Abstract-The high performance Nb 3 Sn strand produced by Oxford Superconducting Technology (OST) with the Restack Rod Process (RRP) is presently considered as a baseline conductor for the Fermilab's accelerator magnet R&D program. To improve the strand stability in the current and field range expected in magnet models, the number of subelements in the strand was increased by a factor of two (from 54 to 108), which resulted in a smaller effective filament size. The performance of the 1.0 and 0.7 mm strands of this design was studied using virgin and deformed strand samples. 27-strand Rutherford cables made of 1 mm strand were also tested using a superconducting transformer, small racetrack and 1-m shell-type dipole coils. This paper presents the RRP strand and cable parameters, and reports the results of strand, cable and coil testing.

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