Today's Progress 11. July. 2007

Possible improvement of proton/deuteron selection procedure on side arm

Until now, the proton/deuteron events were separated with correlations between 1/&beta and total light output on PB+NT. However, we met substantial high-energy background component on inclusive deuteron momentum spectrum, which may be mainly attributed to contamination of proton. Re-considering the summing up procedure of light output, we expect some improvement on the proton/deuteron PID. Here, we develop it step-by-step.

Method

Old procedure - just sum up the light output from all TDCwise fired segments on a arm. When an accidental/physical neutron fires some segments, the correlation between 1/&beta and total light output as proton/deuteron would be broken. The proton+neutron event contaminates deuteron. PB Light output is just calculated from the segment gives 1/&beta / max light output.

New procedure 1 - improvement on NT. The light output is summed up only if fired PB segment and NT row is consistent.

Comparison between old and new procedure 1

Here, let we compare the distribution of proton/deuteron ID functions before and after the improved operation, arm-by-arm, cycle-by-cycle.

Proton/deuteron ID function

Below, the following coloring conventions are adopted to show proton/deuteron ID functions:

Black: all with new procedure.

Red: all with old procedure.

Green: proton/deuteron component with new procedure.

Magenta: proton/deuteron component with old procedure.

E549 cycle results.
E570 1st cycle results.
E570 2nd cycle results.

The cycle-by-cycle proton/deuteron yield with old/new selection procedures are tabulatted below.

cycle-by-cycle proton/deuteron yield with old/new selection procedure.
Arm/cycle E549 E570 1st cycle E570 2nd cycle
Larm p:609386->618070 d:28423->24290 p:623676->632709 d:29126->24801 p:250051->253447 d:11577->9912
Rarm p:595332->602727 d:27613->23479 p:611346->619919 d:27853->23581 p:242712->245819 d:11009->9398

Inclusive deuteron momentum spectrum

Below, the following coloring conventions are adopted to show deuteron inclusive momentum spectra:

Black: with old procedure.

Red: with new procedure.

Green: spectrum with old procedure - spectrum with new procedure

E549 cycle results.
E570 1st cycle results.
E570 2nd cycle results.
Comparison with E549+E570 100% statistics.

New procedure 2

As shown below, we still have some room to improve proton/deuteron ID.
PID functions from L/R arms. The top row is the plot if PB multiplicity is 1 on an arm, and the bottom row is the plot if PB mulitiplicity is more than 2. The left column is for proton ID function, while the right for deuteron.

The lower-tail component on the multiplicity more than 2 is due to the lack of the light output from PB segment fired at the same time, being located just next to the segment which gives max energy loss and stop timing on PB. Therefore, we try to sum up the contribution from the segment. The result is shown below.

PID functions from L/R arms. The top row is the plot if PB multiplicity is 1 on an arm, and the bottom row is the plot if PB mulitiplicity is more than 2. The left column is for proton ID function, while the right for deuteron.

The lower tail dissappeared now. Hereafter, we adopt this improvement to calculate total light output on side arms. The cycle-by-cycle proton/deuteron yield with old/new selection procedures are tabulatted below.

cycle-by-cycle proton/deuteron yield with old/new selection procedure.
Arm/cycleE549 E570 1st cycle E570 2nd cycle
Larm p:618070->624037 d:24290->24704 p:632709->638313 d:24801->25229 p:253447->255742 d:9912->10103
Rarm p:602727->608784 d:23479->23925 p:619919->626327 d:23581->24000 p:245819->248300 d:9398->9590

New procedure 3

We try to improve PID procedure a little bit more. Until now, the summation of light output on NT is taken just checking row ID, as was introduced on the section for new procedure 1. Now, we treat them more carefully as follows:

  • NT 1st layer: light output is accumulated only if consistent PB is fired. This definition is just identical for that of procedure 1.
  • NT 2nd~7th layers: i-th layer light output is accumulated only if the (i-1)-th layer is fired. As the (i-1)-th layer hit, (identical row .OR. row nearby the target) is recognized, as shown below.
    • Schematic figure of procedure 3. The sky-blue is used for the segments from which the light outputs used to be accumulated at the stage of procedure 1, but eliminated from the procedure 3.

    The resulting proton/deuteron yield and deuteron spectra are shown and compared to old results below.

    cycle-by-cycle proton/deuteron yield with old/new selection procedure.
    Arm/cycleE549 E570 1st cycle E570 2nd cycle
    Larm p:624037->624478 d:24704->23744 p:638313->638939 d:25229->24037 p:255742->255977 d:10103->9692
    Rarm p:608784->609277 d:23925->22869 p:626327->626942 d:24000->22932 p:248300->248339 d:9590->9185
    Comparioson of the deuteron spectra before(black) and after(green) the activation of procedure 3. The difference is shown by green.

    Hereafter, we activate all of 3 procedures for PID of proton/deuteron.