The development of the designs and concepts of the target polarization measurement

A.V Aldushchenkov, A.G. Dernyatin, A.I. Kovalev, D.V. Novinsky, I. Okunev, V.A. Shchedrov, V.V. Sumachev, V.Yu. Trautman.

Petersburg Nuclear Physics Institute, Gatchina, Leningrad district, 188350, Russia. E-mail : dimanov@pnpi.spb.ru

I.G. Alekseev, P.E. Budkovsky, V.P. Kanavets, L.I. Koroleva, B.V. Morozov, V.M. Nesterov, V.V. Ryltsov, D.N. Svirida, A.D. Sulimov.

Institute for Theoretical and Experimental Physics, Moscow, 117218, Russia.

N.A. Bazhanov, E.I. Bunyatova

Joint Institute for Nuclear Research, Dubna, Moscow district, 141980, Russia.

D. Novinsky (PNPI)

Preface. For nearest 10 years PNPI-ITEP-Dubna collaboration is planning to measure polarization parameters for N-elastic scattering it follows that we should make the modernization of our experimental setup especially to modernize the proton target polarization measurement.

The experimental setup. Requirements to the polarized target modernization.PCI-cards and power supply source of superconductive coils.Algorithm of the polarization measurement.Conclusions and acknowledgements.

Contents

D. Novinsky (PNPI)

Contents

Until recent time the polarization parameters (P, R, A) measurement results above pion momentum above 1000 MeV/c made it possible to resolve part of discrete ambiguities in existing partial-wave analyses (PWA’s) so we need to continue our investigations.The polarization experiments at N-elastic scattering use the proton polarized target in which free protons have vertical polarization or polarization in the elastic scattering plane.Uncertainty (abs.) is ±~2% at 70% of polarization magnitude.The area under the PMR curve is determined using a Q meter, the measuring circuit of which is excited by a high-frequency fixed-amplitude current, and CAMAC-standard digital measuring equipment, which is connected to computers.It is needed to make the modernization on the base of PC-cards.

Preface

D. Novinsky (PNPI)

Preface

Experimental Setup

D. Novinsky (PNPI)

MAIN ELEMENTS: Vertically polarized proton target PT 4 sets of wire chambers for tracking Trigger scintillation counters

TARGET: Cylinder 30mm, h=30mm, propanediole C3H8O2, free proton density 10 % Magnetic field 2.5 T 3He evaporation type cryostat at 0.5 K Dynamic nuclear orientation Polarization (70-80) %, measurement accuracy ±2 % Sign reverse once per day

Beam Arm

Proton Arm

Pion Arm I

Pion Arm II

Pion Beam

Electronic providing of the polarized target

the area under the PMR curve is determined using a Q meter the measuring circuit of which is excited by a high-frequency fixed-amplitude current Remote computer PC1 contains a crate controller board and exercises direct control over the measuring system through the CAMAC crate An RF generator controlled by the sweep DAC produces a saw-tooth sweep ADC measures the voltage across the Q meter in each scanning cycle This system also comprises four adjustment DAC: tuning reference voltage phase, to adjust the measuring circuit, to select the PMR frequency (the RF generator frequency) and to control the magnetic field

D. Novinsky (PNPI)

Requirements for target modernization

To use the modern digital electronics (PCI-cards) instead of old one on the base of CAMAC.These PCI cards should request to the next conditions:PCI standard, two PCI-cards.One ADC with resolution ≥ 14 bits, digitalization is run by timer, FIFO and transformation time ≤ 8 s; two DACs with resolution ≥ 14 bits,;8-channel DAC 14-bit resolution;To avoid an old operation systems (e.g DOS);Power supply for superconducting coils: compact and to provide more accuracy step along the frequency.

D. Novinsky (PNPI)

PCI-card PCI-DAS6036 (MCC)

Low-cost, 16-channel, 200 kS/s analog I/O boards with two 16-bit analog outputs, eight digital I/O, and two counter/timers

16 channels of 16-bit A/D resolution200 kS/s maximum sample rate2 channels of 16-bit D/A at 10 kHz8 bits DIO 2 16-bit counters

D. Novinsky (PNPI)

PCI-card PCI-1723 (Advantech)

16-bit, 8-channel Non-isolated Analog Output CardMain Features Auto calibration function A 16-bit DAC is equipped for each analog output channel Synchronized output function Output values retained after system hot reset 2-port (16-channel) user-defined digital input/output Board ID

D. Novinsky (PNPI)

Electronic providing of the polarized target

Two PCI-cards are inserted into the PC-board (Remote computer PC1 ). Usage of PCI-card DAS6036 and the PCI-card PCI-1723ADC and DAC with grade ≥ 14 bit, transformation is run by timer FIFO Transformation time ≤ 8 s Usage of the new current source “Lambda-Genesys” for power supply

of superconductive coils, provides step 15 kHz, no noise on the signal sensitivity level (0.3 V)

D. Novinsky (PNPI)

Algorithm of the polarization measurement

The measuring system program is assigned to run with two signals, temperature sensor, sweep DAC and four tuning DACs.

Q-meter, one or two PC, PCI-cards instead of “old” CAMAC. Sweep DAC handles by HF pulser generating saw-tooth sweep and ADC (input

of the phase detector) starts to run by timer. Signal is scanned for 10 s. Q-meter output voltage is measured by means of ADC at each scanning cycle. DACs: one to tune the reference voltage phase of the phase detector, one to

adjust the measuring circuit, one to select the PMR frequency (the HF generator frequency), and one to control the magnetic field.

Total digitalization time ~ 80 s. Data taking (e.g. 100 events) ADC ADC periodically switches to the linear

regime, tuning Q-meter contour. Scanned spectrum is analyzed. The constant component is subtracted from the

spectrum obtained thereby, the area under the resultant curve is computed, and this area is converted into the polarization value.

D. Novinsky (PNPI)

Conclusions and acknowledgements

Now the measurement system is in the progress in usage of PCI-cards

and the new source for superconductive coils power supply works

perfectly. New tests are proposed this year. International collaboration (“Polarized target”)?

Our thanks to RFBR 02-02-16121 and 04-02-16335. GREAT THANKS to the Organizing Committee

of this interesting conference ! ! !

D. Novinsky (PNPI)