Summary of the E2 Run

E2 Run Summary

Stepan Stepanyan

Presentation on CLAS collaboration meeting, June 3-5

E2 run includes seven proposals of multihadron physics group.

Six of this proposals were included in the single package PR-91-009.

The package was approved to run for 800 hours.

38 days of running was scheduled to run from April 15 until May 28.

(456 hours of running with 50% efficiency)

Run coordinators (ECO) - Stepan Stepanyan, Larry Weinstein, Dave Rowntree, Maurik Holtrop, Tony Forest.

Chief of Operation (COP) - Mac Mestayer, Mark Ito.

Physics proposals:

E89015 - Study of Coincidence Reactions in the Dip and Delta-Resonance Regions (Hossain Baghaei)

E89017 - Electroexcitation of the Delta(1232) in Nuclei (Richard Sealock).

E89027 - Coincidence Reaction Studies with the LAS (William Bertozzi, Werner Boeglin, Lawrence Weinstein)

E89031 - Study of Multi-Nucleon Knockout With the CEBAF Large Acceptance Spectrometer (Bill Hersman, Jack Lightbody, Rory Miskimen).

E89032 - Study of the Local Properties of Nuclear Matter in Electron-Nucleus and Photon-Nucleus Interactions with Backward Particle Production Using the CLAS Detector (Valdimir Gavrilov, Georgy Leksin).

E89036 - Study of Short-Range Properties of Nuclear Matter in Electron-Nucleus and Photon-Nucleus Interactions with Backward Particle Production using the CLAS Detector (Kim Egiyan).

E98104 - Measurement of the polarized electron beam asymmetry on exclusive reactions in nuclei with CLAS (Bill Hersman, Maurik Holtrop).

Proposed run plan for e2 (4/15 - 5/28)


Dates	Ebeam (GeV)	Target	It (A)	Im (A)	Comments
4/13-4/14	Maint.				Put the heat shield
4/15 -	4.4	⁵⁶Fe	2250	6000	Beam tune 4 hours test run with 4He 4 hours 1 day Molybdenum shield is in
		⁴He	2250		6 days Molybdenum shield is out
- 4/26	4.4	¹²C	2250	6000	4 days
4/27-4/29	Maint.				3 days Cange the cell if needed
4/30-5/04	4.4	³He	2250	6000	5days
5/05-	1.1	3He	750		.7 days
-5/07	1.1	12C	750	6000	.3 days
5/08-5/13	Facil.D.		Maint		3/3 days
05/14 -	2.2	4He	2250	6000	5 days
		3He	2250		5 days Change 4He to H2
- 5/28	2.2	12C	2250	6000	4 days

Conditions:

Trigger EC only at 4.4 GeV, EC*CC at 2.2 GeV and 1.1 GeV;
Moller runs every 2 days;
Empty target runs - about 5% of He data;
CH2 runs at 4.4 GeV and 1.1 GeV for calibration;
Hydrogen run at 2.2 GeV for calibration;

Run plan for e2 (4/15 - 5/28)


Dates	Ebeam (GeV)	Target	It (A)	Im (A)	Comments
4/13-4/14	Maint.				Put the heat shield
4/15 -	4.4	56Fe	2250	6000	1 day Molybdenum shield is in
		4He	2250		6 days Molybdenum shield is out
- 4/26	4.4	12C	2250	6000	4 days
4/27-4/29	Maint.				3 days
5/1 -	2.2	12C	2250	6000	5 days
5/04		Target	is	back	1 day
- 5/10	2.2	4He	2250	6000	6 days
5/11-5/13			Maint		3 days
05/14 -	1.1	12C	1500 750	6000	1 days
- 5/18	1.1	3He	1500/ 750		2 days
5/18 - 5/23	2.2	3He	2250		5 days
5/24 - 5/27	4.4	12C	2250	6000	3 days

Conditions:

Trigger EC only at 4.4 GeV, EC*CC at 2.2 GeV and 1.1 GeV;

Moller runs every 2 days;

Empty target runs - about 5% of He data;

CH2 runs at 4.4 GeV, 2.2 GeV and 1.1 GeV for calibration;

He + 12C runs for calibration;

E2 targets -

Beam current at 4.4/2.2/1.1 (nA)

¹²C d = 0.1cm L = 0.85x10³³/nA 10/15/6

56Fe d = 0.015cm L = 0.44x10³³/nA 10/10

CH₂ d = 0.07cm L = 0.35x10³³/nA 10/12

⁴He d = 5.cm L = 2.35x10³³/nA 4.5/6

³He d = 5.cm L = 1.2x10³³/nA 10/11/5

Empty (4 types) d = 0.005cm L = 0.05x1033/nA 35/35/32

Unstable liquid targets with fluctuating density in the cell.

Measurements with combined liquid and solid targets have been made to estimate systematics of the fluctuations.

The main events during the run -

Smooth running on 56Fe, 12C and 4He at 4.4 until April 27;

Melted cryostat repair during April 27 - May 4;

Running on pure solid targets;
Excellent work have been done by Dave Kashy and the group.

First cell was ruptured on May 7;

Target repair during weekends (as usual);

Continue running on 4He at 2.2 GeV on May 8;

Second cell collapsed on May 11;

New cell was in place on May 12;

New cell was leak was repaired during the weekends (as usual);

Then running 3He (mostly) at 1.1 GeV, 2.2 GeV and 4.4 GeV from May 20 to May 27.

Exelent work have been done by Dave Kashy and the group (as usual).

The main problems:

CryoTargtes:

Control for He targets;

Allocated time for configuration change;

Beam tuning and stability:

RF trips (~100/shift);

Orbit locks on BPM's 2C24 and 2H01 (worked well on the end);

CLAS performance:

Mini-torus (power supply UPS);

DC ADB crates;

Dead channels in DC, CC, EC and SC;

Summary of the run:

CLAS performance was very good

Engineering group did excellent job on the target;

Hall B staff did grate job keeping detector operational;

CLAS collaborators did fill shifts and did in fact grate job;

E2 group did very well in the coordinating and the monitoring the run;

Accelerator control group delivered excellent beam (almost always);

Although there were many problems and beam time lost we were able to -

collect 2303M triggers in the 4278 files of 365 runs.

E2 Run Summary

The next step -

Calibrate ( ~ 3 month) and process data.