References - Bogoliubov Laboratory of Theoretical Physics - JINR

6. Estimate of the count rate in transmission measurements using new SPD.
An expression for the measured −ΔσL,T (np) value is following
−σL,T =ln[(M − T + )/(M + T − )]/(|PBPT |nH), (6.1)
where the M + , M − and T + , T − are the statistics for monitor and transmission neutron
detectors with the P +
B
and P −
B neutron beam polarizations, respectively. The PT is the
polarized proton target polarization value and nH is the number of polarizable hydrogen
atoms at polarized proton target.
A systematic uncertainty of the −ΔσL,T valueismainlycausedbytheerrorsin|PB|,
|PT |, andnH. The statistical error of −ΔσL,T is given by the formula
δstat = � (1/M + +1/M − +1/T + +1/T − )/(|PB PT | nH). (6.2)
where the M + , M − and T + , T − are the statictics for monitor and transmission neutron
detectors with the P +
B
and P −
B
neutron beam polarizations, respectively.
To estimate the required statistics for the monitor neutron detectors M in order to
reach desired value of the ΔσL,T statistical error δstat, we substitute the experimentally
obtained nH, |PB|, |PT |, andT/M values [7 - 8] in to this formula:
nH =9.14 × 10 23 ; |PB| =0.5; |PT | = 07; T/M =0.82.
To reach the δstat value of ∼ 1 mb it is required to accumulate the M statistics equal
to ∼ 4.5 × 10 7 counts. From our experience obtained during the np charge-exchange
measurements [9 - 10] using high intensity (∼ 2 × 10 10 particles per cycle) unpolarized
deuteron beam, such M statistics will be accumulated within 8 hours approximately.
Therefore to measure the −ΔσT values at 10 points of the neutron beam energy Tn it is
required about ∼ 80 hours of the ”pure” run time for statistics accumulation. The count
rate which will be accessible with new source of polarized deuteron ions at the Nuclotron-
M estimated above, allows obtaining the −ΔσT values with very high precision [14].
References
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[13] L. Sidorin. ”Nuclotron-M project: Status and the nearest plans”. Talk at the LHEP Scientific-
Technical Council. April 16, 2009.
[14] V.I. Sharov. The new project proposal ”Measurements of the total cross section difference ΔσT (np)
and spin-correlation parameter Aoonn(np) at the Nuclotron-M”. (Delta-Sigma-T). Dubna, 2009.
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