Impact of the Coulomb field on charged-pion spectra in few-GeV heavy-ion collisions

In nuclear collisions the incident protons generate a Coulomb field which acts on produced charged particles. The impact of these interactions on charged-pion transverse-mass and rapidity spectra, as well as on pion–pion momentum correlations is investigated in Au + Au collisions at $\sqrt{^{S}NN}$ = 2.4 GeV. We show that the low-m$_{t}$ region (m$_{t}$ < 0.2 GeV / c$^{2}$) can be well described with a Coulomb-modified Boltzmann distribution that also takes changes of the Coulomb field during the expansion of the fireball into account. The observed centrality dependence of the fitted mean Coulomb potential energy deviates strongly from a $A_{part}^{2/3}$ scaling, indicating that, next to the fireball, the non-interacting charged spectators have to be taken into account. For the most central collisions, the Coulomb modifications of the HBT source radii are found to be consistent with the potential extracted from the single-pion transverse-mass distributions. This finding suggests that the region of homogeneity obtained from two-pion correlations coincides with the region in which the pions freeze-out. Using the inferred mean-square radius of the charge distribution at freeze-out, we have deduced a baryon density, in fair agreement with values obtained from statistical hadronization model fits to the particle yields

High Voltage Piezo Driver RTM and its Application

A MicroTCA.4 (MTCA.4) compliant Piezo Driver (DRTM-PZT4) has been developed to drive piezoelectric-based actuators used in accelerator instrumentation applications. More specifically, it is used for synchronization of pulsed lasers, stabilization of fiber links, piezo based motor driver control and superconducting cavities fine tuning. This paper briefly presents the designed system requirements and discusses the main hardware components and their latest improvements. The results of the designed hardware usage for various application are summarized

A Novel Approach for Hardware Implementation of a Detuning Compensation Control System for SC Cavities

Superconducting (SC) resonant cavities seems to be an attractive option for various linear accelerators under construction. The nine-cell 1.3 GHz cavities have demonstrated gradients up to 38 MV/m. They are susceptible to small changes of dimension caused by mechanical vibrations, cooling systems, human activity (microphonics) and high gradients of RF field (Lorentz forces) as well. FPGA-based control system for cavity detuning compensation is presented

High Voltage Power Module Pluggable to NAT RTM Power Supply Carrier

In the paper we want to present High Voltage Power Module (HVPM) pluggable to Micro Telecommunication Computing Architecture generation four (MTCA.4) based Rear Transition Module (RTM) Power Supply Carrier (PSC) and its possible applications. The idea is to have a possiblity to power supply RTM cards that demands specific voltages above 12VDC. The HVPM module is composed of high voltage dc/dc bricks and onboard diagnostics. The dc/dc power modules are designed to make up conversion from 48VDC input voltage to demand +/-100VDC output voltage. The 48VDC input voltage is generated by the PSC using 220VAC input voltage. The onboad diagnostics allow monitoring temperature of the modules, output power, voltage as well as current consumption when operated under load condition. The HVPM is pluggable to RTM PSC and communicates with the carrier using standard i2c bus communication protocol. The HVPM maintanance can be obtained using debug serial console available directly from the carrier or using the MicroTCA Carrier Hub (MCH) installed on the front of the standard MTCA.4 crate

MTCA.4-Based Beam Line Stabilization Application

We want to summarize the beam line stabilization application with MTCA.4 electronics. Presented solution is based on the compact 2U MTCA.4 crate integrating sensor and actuator cards. The optical beam position sensor is based on quadrupole SI PIN photodiode connected to low cost AMC based FMC carrier equipped with ADC card. The optical beam position correction is done using picomotorized stages equipped with active piezo elements and high voltage RTM piezo driver. The data processing and digital feedback units are implemented using Spartan 6 FPGA. The control algorithm has been optimized for low latency and high precision computations. The control electronics performance has been tested using single beam line test stand consisted of commercial laser diode drivers, supported optics and motorized stages. The first results are demonstrated and future possible applications are briefly discussed