Today's Progress 13. July. 2006

Study of (stopped K^-, X^0) spectrum with T0-NT (2)

By using the T0-PA-PB then PA-NT TOF analysis, now T0/NT offsets had been accurately studied, and, Kstop events are now confiently identified. Here, we examine the availability of the offsets and correction functions obtained by Kmu2 events to the gamma-ray events, again.

Determination of slewing correction function with Compton-gamma-events

Method

For the 100% production runs, we study the time residual,

deltaT(T0->NT) = Tnt - Tt0 -TOFkstop ,

for neutral particles. Firstly, charged-particle-defined Tnt is examined.

Result

T0->NT 1/beta resolution defined as the Gaussian &sigma to fit the peak of Compton-like &gamma when Kmu2-determined correction functions and offsets are applied as they are.

T0->NT 1/beta Gaussian center when Kmu2-determined correction functions and offsets are applied as they are for Compton-like &gammma.

T0->NT 1/beta resolution defined as the Gaussian &sigma to fit the peak of shower-like &gamma when Kmu2-determined correction functions and offsets are applied as they are.

T0->NT 1/beta Gaussian center when Kmu2-determined correction functions and offsets are applied as they are for shower-like gamma.

PA-NT residual for K^+-Kmu2(top) and T0-NT residual for gamma(bottom), if Kmu2-determined slewing correction has been applied.

The correlation between sqrt(phu*ph) PA-NT residual for K^+-Kmu2(left) and T0-NT residual for gamma(right), if Kmu2-determined slewing correction has been applied.

The correlation between 1/sqrt(E) (horizontal) and PA-NT time residual for stopped K^+ (black)/T0-NT time residual for stopped K^- (red).

As already reported, following two facts are clearly found when Kmu2-determined corrections are applied for GAMMA RAY as they are:

1/beta center is deviated to the faster side in segment-dependent way.

Substantial correlation between energy and time remains.

Note that they are still open problem whether they are also true for neutron, or not.

Nextly, we re-tune the offset and correction function to optimize for Compton-like GAMMA RAY.

T0->NT 1/beta resolution defined as the Gaussian sigma to fit the peak of Compton-like gamma-ray when gamma-determined correction functions and offsets are applied.

T0->NT 1/beta Center of Gaussian to fit the peak of Compton-like gamma-ray when gamma-determined correction functions and offsets are applied.

T0->NT 1/beta resolution defined as the Gaussian sigma to fit the peak of NOT shower-like gamma-ray when gamma-determined correction functions and offsets are applied.

T0->NT 1/beta Center of Gaussian to fit the peak of shower-like gamma-ray when gamma-determined correction functions and offsets are applied. Substantial deviation from 1.0 is seen.

A substantial deviation of beta-inverse center is found for shower-like gamma-ray, and the tendency of the deviation is opposite to the expected from the possible overcounting of the TOF distance. This fact is known since E471.

Energy dependence of 1/beta peak center and Gaussian width/Layer-by-layer resolution plot are exhibitted below, for Compton-like gamma-ray with Compton-gamma-determined slewing correction function.

Arm-by-arm energy dependence of Gaussian width of Compton-like gamma-ray events (left) and the dependence of Gaussian center (right). Left and right arm results are plotted by black and red, respectively.