Transcript Novinsky

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 : [email protected]
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)
Contents
Contents
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.
D. Novinsky (PNPI)
Preface
Preface
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.
D. Novinsky (PNPI)
Experimental Setup
MAIN ELEMENTS:
 Vertically polarized
proton target PT
 4 sets of wire
chambers for tracking
 Trigger scintillation
counters
Beam Arm
Pion Beam
Proton Arm
Pion Arm I
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
D. Novinsky (PNPI)
Pion Arm II
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 resolution
200 kS/s maximum sample rate
2 channels of 16-bit D/A at 10 kHz
8 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-1723
ADC 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
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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)