DC status, 18.07.2007, je 1

16 DC’s on the support !!

DC status, 18.07.2007, je 2

4 Levels of test

1. Pretest HV Air + tightness

2. Aquarium : functionality + tightness

3. Cosmics Lab : other preamps + correct signal assignment inside COBRA up to panel== preamp calibration

4. Cosmics E5, with and without COBRA== preamp calibration + alignment

17 DC‘s through level 2 + 13 DC‘s through level 3 + 3 DC’s partially level 3

DC status, 18.07.2007, je 3

Tightness

a) Clean old pair with He

b) New DC pair in

c) Flush with 50%-50%

HV in pure He (Aquarium closed)

• As above

• Flush He in Aquarium

• Open Aquarium

49.5%

48.6 %

~1 %

DC status, 18.07.2007, je 4

Sr90 , slits of > 5 cm

a) All signals present (anode asymmetry only if up and down)

b) Circle only with 4 correct cathodes

c) separation of 2 periods

Assy cath up

Assy cath down

Assy anodes

DC status, 18.07.2007, je 5

Calibration

AsyAn0 = [{(l/2+x)r + R} - {(l/2-x)r + R}] / [{(l/2+x)r + R} +{(l/2-x)r + R}]

= 2x / ( l + R/r)

AsyCat/(sum anode) = a+bsin(2*pix/period + phase)

DC geometry Ok to +-.05 mm

Iteratively : a) Project with and optimize ratio of anode preamp gain or thin slit in the middle

b) Fit cathn /(sum Anode)

Clever fit like Boris and Sacha

DC status, 18.07.2007, je 6

DC status, 18.07.2007, je 7

DC status, 18.07.2007, je 8

DC test with Cosmic ray (in Lab.)

DC status, 18.07.2007, je 9

DC status, 18.07.2007, je 10

cosmic ray counters for DC wire alignment• 10 counters (10 plastic scintillators + 20 PMTs) are prepared

• DC wire alignment will be performed w/o COBRA field

DC status, 18.07.2007, je 11

•event rate is estimated by MC

•beyond hit rate map is corresponding to 5 hours running

•“1 counter hit & 2 DC hit” are required

•if we request 10k tracks for 1 wire at least, 90 hours are necessary

cosmic ray counter for DC wire alignment (2)

# o

f hit

/ 5

hours

DC status, 18.07.2007, je 12

cosmic ray in the COBRA field• event examples

μ+ : 746MeV/c μ- : 607MeV/c

DC status, 18.07.2007, je 13

DC trigger (Michel)== energy and resolution calib.

01

23

45

67

8

910

11

12

13

14

15

16

17

•optional trigger :

(1)standard trigger + 1 hit in the “outer sector”

(2)standard trigger + TC hit (bar & fibre)

inner

outer

e+

The definition of the standard Michel trigger :just requiring the # of hit sector ≥ 4 , does NOT care “inner/outer”

DC status, 18.07.2007, je 14

momentum spectra (standard trigger)

DC status, 18.07.2007, je 15

momentum spectra (optional trigger)

DC status, 18.07.2007, je 16

Control of DC geometry

a) 2 print crosses measured relative to reference bolts in mech. Workshop

b) Same in COBRA by survey group

• On the platform

• Without end cap

• (next days !)

• Without COBRA

DC status, 18.07.2007, je 17

photos

DC status, 18.07.2007, je 18

photos

DC status, 18.07.2007, je 19

Backgrounds

a) HV units, disappear with linear regulator for low supply

b) “Front end program” not polling but online time calibration

c) Up-down negligible with better up-down print grounding

• print ground to metallic cover of Carbon support

• Al contact between frames from up support to down support

d) Rate (temperature) dependence of DRS calibration next Chip

DC status, 18.07.2007, je 20

Data reduction

reject cells

a) peak to peak of anode sum < 2*threshold in time window

b) 2 neighbors with peak to peak of anode sum < 2*threshold in time window

Data reduction with limit on peak to peak [cosmic]

0

0.2

0.4

0.6

0.8

1

1.2

0 20 40 60 80 100 120

4a/trigger[%]

4A+4B)/trigger[%]

datasize/event/DC[%] 115 kB at 0

DC status, 18.07.2007, je 21

Second optimistic migration possibility to COBRA : today

Realistic migration to COBRA : Thursday, Friday

Aquarium

a) flushing gas (5 hours) + HV (last 3 hours of gas flushing)

b) measurement and analysis (2 hours )

c) flush He in Aquarium (3 hours)

d) eventually measurement and analysis( 2 Hours)

total of 12 Hours

Support

a) flushing gas (7 hours) + HV (last <3 hours of gas flushing)

b) measurement and analysis of previous run (3-6 hours 40000 events)

c) change connection and cosmic Scintillator position(1 hour)

Total of 11 hours for the first after Aquarium run, < 7 hours for the others ( without repair)

DC status, 18.07.2007, je 22

1. Finish testing on support

2. Transport and insert in COBRA

3. Measure geometry by survey group

4. Cabling in E5 2 days

5. Test DAQ complete system

6. Cosmic without COBRA field (alignment)

7. Cosmic with COBRA field (when COBRA on)

> 4 working days

DC status, 18.07.2007, je 23

End

DC status, 18.07.2007, je 24

photos

DC status, 18.07.2007, je 25

photos