BPM System for Transport Channel BoosterNuclotron at NICA

BPM System for Transport Channel Booster–Nuclotron at NICA Complex Е. Bekhtenev (BINP SB RAS, Novosibirsk),

Transfer line Booster - Nuclotron The NICA are two synchrotron rings: Booster and Nuclotron. Both are located in the same tunnel, but different level. Beam paremetres Ions: before stripping after stripping Ion numbers: Booster out Nuclotron in Charge after stripping: nominal minimal RMS bunch length: RMS bunch time: Au 31+ Au 79+ 1, 5 109 1, 3 109 ~16 n. C ~0. 016 n. C 20. 94 м 89 ns

Beam Position System in Channel BPM sytem consist of 6 electrostatic pickups and electronics. Pickups have two different size. Technical requrements for beam measurement system Beam charge: Repetition frequency: accuracy: 0. 016 - 16 n. C ~0. 25 Hz 1% half aperture (0. 6/0. 3 мм)

Electrostatic pickup BPM design provide good linearity. BPM parametrs Parametr GX, GY – horizontal and vertical multiplier BPM 1 -3 Пикапы 4 -6 Aperture 125 мм 60 мм Length 125 мм 60 мм Capacity ~12 p. F ~10 p. F Multiplier GX, GY ~69 мм ~33 мм Signal for charge 16 н. Кл * ~0. 6 В ~0. 3 В Vacuum feedthrough SMA Nonlinearity ~1 % * estimate

Results of calculation Nonlinearity across the aperture 1 % After fabrication all BPMs will be measured at the special stand.

BPM parameter measurement For every BPM will be measurement the coordinate grid and calculated zero offset and multipliers. Test stand in BINP.

Electronics consist of the Preamplifer, near BPM and BPM processor module located in safe room.

Signal processing 4 arrays signals are send to the control computer, where it is processed further. The processing includes optimal filtration with finding of signal maximum. It is possible separate beam position measurement of “head” and “tail” of the bunch.

Time diagram of BPM processor operation BPM signal Calibration signals U 75µs t 300µs 4 calibrating pulses are used to increase signal-to-noise ratio for calibration. Large time between beam injection to Nuclotron(4 sec) can be used for generation and measurement of the calibrating pulses for additional increasing of signal/noise ratio.

BPM processor parametrs parameter value Bandwidth ~4 MHz Gain range 0 – 30 d. B Gain step 1 d. B Input impedance noise frequency ~50 Ω ~3 n. V/√Hz 60 MHz Gain range of the calibration signal 0 – 30 d. B Gain step of the calibration signal 1 d. B Ethernet 100 Mb/sec

BPM processor prototype Front side power 220 В 50 Гц. Rear side

Network connections

Preamplifier Parameter bandwidth value ~100 MHz Gain 3/30 d. B Input capacity ~10 p. F Noise Connector ~5 n. V/√Hz SMA Low noise amplifier has JFET-input stage with low input voltage noise.

Preamplifier This preamplifier satisfies to technical requirements. The only problem may be a radiation presence in the transport channel. It can influence preamplifier reliability The second type of preamplifier with minimum of electronic components has been developed and tested.

preamplifier (type 2) parameters Gain Input capacity value ~0. 7 ~10 p. F Preamplifier noise ~2 n. V/√Hz Preamplifier and BPM processor noise ~5 n. V/√Hz connector SMA

Measurement accuracy Absolute beam position measurements accuracy is defined: 1) BPM zero offset (it is minimized by test stand) 2) BPM position error in channel 3) Zero shift caused by electronics (in calibrating circuits) 4) Relative accuracy of measurements defined by electronics Relative beam position measurement accuracy is defined by: 1) Random measurement error caused by electronics noise and interferences 2) Dependence of measurement result on temperature 3) Dependence of measurement result on beam charge The measurement errors have been evaluated during testing with using of pulse generator Agilent 81110 A.

BPM Resolution resolution, мкм 10000 100 10 0, 01 0, 1 1 Beam charge, н. Кл 10 100 Dependence of measurement resolution vs the beam charge

Measurement accuracy Parameter Type 1 preamplifier Type 2 preamplifier ~10 мкм ~100 мкм ~1200 мкм Dependence of measurement result on temperature in the temperature range 20 - 40°С < 100 мкм < 200 мкм Dependence of measurement result on the beam charge in the charge range 0. 02 – 16 н. Кл < 200 мкм < 500 мкм resolution: Beam charge > 5 н. Кл Beam charge 0. 3 н. Кл Beam charge 0. 02 н. Кл

State of things At present two variants of the BPMs are designed, The prototypes of BPM electronics has been fabricated and tested. It is planned in 2018 to produce all BPMs and electronics.