Strangeness enhancement at mid-rapidity in Pb-Pb collisions at 158 GeV/c

$K^{0}_{s}$, $\Lambda$, $\Xi$, $\Omega$ and negative particle yields and transverse mass spectra have been measured at central rapidity in Pb-Pb and p-Pb collisions at 158 $A$ GeV/$c$. The yields in Pb-Pb interactions % are presented as a function of the collision centrality and compared with those obtained from p-Pb collisions. Strangeness enhancement in Pb-Pb relative to p-Pb collisions increases with the strangeness content of the particle. Going from p-Pb to Pb-Pb, the strange particle yields increase faster than linearly with the number of participants $N_{part}$ up to $N_{part} \approx 100$, thereafter the increase becomes %linear with $N_{part}$. Yields are studied as a function of the number of nucleons participating in the collision $N_{part}$, which is estimated with the Glauber model. From p-Pb to Pb-Pb collisions the particle yields per participant increase substantially. The enhancement is more pronounced for multistrange particles, and exceeds an order of magnitude for the $\Omega$. For a number of participants, $N_{part}$, greater than $100$, however, all yields per participant appear to be constant

Determination of the number of wounded nucleons in Pb+Pb collisions at 158 A GeV/c

The charged particle multiplicity distributions measured by two experiments, WA97 and NA57, in Pb+Pb collisions at 158 A GeV/c have been analyzed in the framework of the wounded nucleon model (WNM). We obtain a good description of the data within the centrality range of our samples. This allows us to make use of the measured multiplicities to estimate the number of wounded nucleons of the collision

A Study of Cutting and Forming Threads with Coated HSS Taps

Tapping is a very common machining process for producing internal threads. A tap is a cylindrical or tapered thread cutting tool having threads of a desired form on the periphery. Combining rotary motion with axial motion, a tap cuts or forms the internal thread. Due to desired accuracy and versatility of thread profiles most taps are made of high speed steel. Physical surface coating taps (monolayer, duplex or triplex) increases tap life and improves thread finish. Regarding the CNC canned cycles the demands on safe tool performance of the threads are more and more urgent. This paper deals with a study of 2D surface parameters, Coulomb´s coefficient of friction, energy consumption and cutting/forming performance of selected PVD coated HSS taps when machining of carbon steel C45 and forming of hardened steel 42CrMo4V