February 15th, 2017

Agenda [attended: Avetik, Moskov, Jim, Mikhail, Mark, Chan, Nick, Justin, and Igor]

1) Status of DIRC & impact for KL

• Nick: Looked at theta vs p for the Kaon and pion 4 reactions:

-- KLp-->pi+Sigma0: [1]

-- KLp-->pi0Sigma+: [2]

-- KLp-->pi+Lambda: [3]

For the Lambda reaction, I also decayed the Lambda and looked at the pi- distribution. The same was performed for the Sigma+ reaction (Sigma+ —>n pi+).

-- KLp-->pi+Lambda: [4]

-- KLp-->K+n: [5]

These are pure phase space generated reactions, with the beam momentum taken from the beam profile from Simon (up to ~6 GeV/c).

• Justin: As I expected the DIRC region of interested for the DIRC (theta = 1 - 10 deg and p = 2 - 4 GeV/c) is not a large part of the phase space for these reactions. It should be available to use at that time, but I don’t think it’s a driver for the proposal. A more interesting study would be to understand the pi/K separation provided by the BCAL timing which is where the vast majority of your events will be located.

Installation of the DIRC schedule is: half this summer of 2017 and then second half next summer of 2018.

2) Mikhail: Updated plot of time uncertainty in Be target as a function of KL true momentum is tiny. One can safely neglect it. KL momentum resolution of KL-beam is indeed fully determined by the start counter time resolution [6].

Start counter has 300 ps smearing [7]. 50 ps is difficult but 100 ps will work very well [8]. DeltaW/W plots in linear [9], log scales [10], and in restricted W-range (limited W range W < 2.6 GeV while the full range is W < 3.5 GeV [11]. At the right bottom plot the X axis is W^{true} - true W is in GeV. I have to specify "true" to oppose "reconstructed" W. On Y axis you have W-resolution in %: \sigma(\DeltaW/W)*100.

Moskov: Now one can clearly see that even with 100 ps timing resolution, the W resolution will allow to measure many predicted Cascades*.

3) Igor: Shifting a concrete block in alcove up stream is reducing a neutron effect on the ceiling above GlueX setting (RadCon limit is 1 mrem/h) by significant amount. Additional concrete block will keep us save with electron current 5 uA, tungsten radiator 0.1 r.l., and Be-target 1.7 r.l. Statistics is small and we are still doing MC.

4) Moskov made a brief of his tomorrow talk for the GlueX Collaboration meeting [12].

5) LASS Proposal E-135, 1979 "Comparison of K-p and K+p Interaction, and Programmatic Study of Strange Quark Spectroscopy" [13]

• Jim Napolitano: "The point of the experiment was to make good use of the very pure K- and K+ beams you could get at SLAC, thanks to the RF separation technique and the pulsed electron beam. The main addition was a solenoid (which is now the main magnet for GlueX) and trigger-able proportional chambers surrounding the target, which gave them essentially full 4pi coverage. Almost all of the results were on spectroscopy of strange (or multi strange) particles. They did some excellent work on the excited kaon spectrum, and found a number of new strange baryons, including an excited Omega. These papers should be easy enough for you to find. So far as I’m aware, nobody ever published any results using the K+ beam."

6) Experiment condition [we will not touch a pol target case]:

• Electron Current: 5 uA (60 kW max).
• Bunch spacing: 64 ns.
• W-radiator: 0.1 r.l.
• Be-target: 1.7 r.l. (length: 40 cm, radius: 3 cm).
• p = 0.3 - 10 GeV/c (measured by TOF).
• dp/p: ~1%.
• KL flux: ~3 x 10^4 KL/s (measured by pair spectrometer).
• Target: LH2/LD2 (length: 30 cm, radius: 3 cm).
• Distance Be-LH2: 16 m.

We have to implement CPS, improve time resolution of the Start Counter to reach 50 - 100 ps, and design the Be-target with plug and concrete block setting. Do we need in a new LH2/LD2 target cell?