P. Arpaia, C. Petrone, S. Russenschuck
MEASURING MULTIPOLE FIELD ERRORS IN MAGNET APERTURES OF LARGE ASPECT RATIO BY MEANS OF AN OSCILLATING WIRE ON ELLIPTIC TRAJECTORIES

Errors in the transversal field of accelerator magnets are usually expressed in terms of the coefficients of a harmonic expansion on a circular trajectory in the magnet’s aperture.
An elliptic trajectory more suited to apertures with large width-to-height ratios allows the field inside the domain to be reconstructed with a higher accuracy. Displacing an oscillating wire along an elliptical trajectory and acquiring the amplitude of the wire oscillation at each point yield a periodic signal to be expanded into the elliptic multipoles. The paper discusses the theoretical background, the practical implementation in the measurement system, and the accuracy achieved in the measurements of a quadrupole magnet.

P. Arpaia, L. Fiscarelli, L. Walckiers
CALIBRATION OF ROTATING COIL ARRAYS FOR PARTICLE ACCELERATOR MAGNET TESTING

Synchrotron particle accelerators are mainly composed of magnets. Long dipole magnets are employed to bend and to contain the beam within a circular trajectory. Their field quality is usually tested by arrays of rotating coils. Typically the measurements must be affected by low uncertainty (±10^-4) and the calibration of the sensing coils, in terms of surface and angle, is critical. In this paper, a new method for the coil calibration is presented. The method is firstly stated formally and then validated in an actual use case. Experimental results demonstrate the capability of the method to meet also constraining requirements.

Ján Šaliga, Linus Michaeli, Ján Buša, Jozef Lipták, István Kollár, Tamás Virosztek
EXPERIMENTAL COMPARISON OF MAXIMUM LIKELIHOOD AND LS FITTING FOR ADC TESTING

ADC test methods require the best possible reconstruction of the input signal to the ADC under test from the acquired, therefore erroneous ADC output data. The commonly used LS fit and the recently introduced maximum likelihood estimation are competing methods. This paper presents an experimental comparative study of these estimation methods with the goal to investigate the behaviour of both methods and to determine their limits. An alternative algorithm for the calculation of the maximum likelihood fit is also examined. Some practical recommendations for the choice of optimal method for various conditions of ADC testing are also given as a conclusion of the comparative study.

Dan Mihai Stefanescu, Alexandru-Titus Farcasiu, Adrian Toader
VIRTUAL INSTRUMENTATION AND CANTILEVER BEAM TYPE TRANSDUCER WITH STRAIN GAUGES FOR MEASURING THE DISLODGING FORCES OF REMOVABLE DENTURES OR PALATAL PLATES

The TensoDentar is a complex measurement system of dislodging forces for complete dentures or palatal plates. An original strain gauge force transducer (SGFT) and virtual instrumentation in NI and LabVIEW environment are used conforming to a rigorous clinical protocol to evaluate the efficiency of two surface treatments (sandblasting and plasma treatment) on complete denture base materials. The present work has the unprecedented goal to achieve in vivo comparison of the two techniques. First experimental results obtained are presented and interpreted.

Meng Feng, Zhang Yue, Zhang Zhimin, Li Tao
A NEW MULTIFUNCTION TORQUE STANDARD MACHINE AT NIM

The paper describes a new multifunction torque standard machine at NIM. National institute of Metrology has established a multifunction torque standard machine. It has three main functions. One is hydraulic torque wrench calibration. The second function is torque multiply calibration. The third function is reference torque standard machine. This paper introduces the structure and the working principle of the equipment, performance parameters and the uncertainty evaluation.