1. MEG DC HV supply preamplifier noise and DRS Input attenuation
protection in pure He new print
gas regulation, DC tightness, He-C2H6 ratio
N bag
Calibration
schedule
2/22/2019
DC_status,Je

2. HV supply < 100 V oscillations  OK 8 x 2 channels for dec-run
Tests
Noise – filter
Optimize ramping
Capacitors +DC charge loading
Recovery, isolators polarizing time
2/22/2019
DC_status

3. preamplifier noise and DRS Input attenuation
s of 400 first DRS channels [mV]
Anode number
For physical big pulse
Ratio e+/big pulse const
For « edge » big pulse
At least rate increas with HV
sqrt([6 V on]2 - [6 V off]2)
2/22/2019
DC_status

4. DC Current-slit behavior OK
Noise important
Max current at 1700 V :
~5 mA
May be 1780 necessary
(first run 2000 V : 60 mA)
2/22/2019
DC_status

5. Noise Much larger than in lab
Much larger than first measurement in PE5
Fast contribution (see Matthias) already found in HV supply as used in December 2007 run
« slow » component { 1-2 ms) needs more work
2/22/2019
DC_status

6. protection in pure He
Capacitors, edges, resistance in pure He (< 2% impurities)
Imbed elements in Araldit,
stable
homogenous
no temperature effect < 65 0
Threebond white and grey ,
needs humidity
temperature effects already at 55 0
Edges better with next print
2/22/2019
DC_status

7. Near wing frame, protection longer
new print
Near wing frame, protection longer
Increase distance Carbon frame to HV lines,not to suffer from Threebond „bad“ isolator properties
 3 layers with wenn possible HV line in the middle layer
2/22/2019
DC_status

8. gas regulation and DC tightness
[Pa]
[Pa]
gas regulation and DC tightness
Pressure sensors S1 S2
Flux in
out
DC‘s
Dpf Dp
manifold
[Pa/(cc/min)]
Dp/(Flux in+ Flux out)
Consistency
Dp/(Flux in+ Flux out) constant
Dpf << Dp
(S1+S2)/2
2/22/2019
DC_status

9. 8 DC connected to manifolds Stabilize at or Ok if not
12 min
Ln Dp
Tightness
4 good
2 not so good
2 bad
8 DC connected to manifolds
Stabilize at or
Ok if not
(not consistent with viscosity air-He)
DC‘s
(S1+S2)/2
Flux out (with Flux in = 50 cc/min)
2/22/2019
DC_status

10. Diffusion of He through Mylar 12 mm 1/2 atm 16x1450 cm2 4.6 cc/min
C2H6
If diffusion
1/180 negligible
If leak
½ cc/min He
.09 p/min
16DC,.5 atm 
.72 cc/min
40 cc/min  2 %
Diffusion of He through Mylar 12 mm 1/2 atm 16x1450 cm2 4.6 cc/min
2/22/2019
DC_status

11. He-C2H6 Ratio dependence
1850 V % He, 50% He, 55.6% He
 < 2 % stability, reproducibility
2/22/2019
DC_status

12. Sensor of He fraction in He-C2H6 mixture
Gas system in Lab
Understand and calibrate system perfectly
Calibration of He content sensor or better suited sensor
2/22/2019
DC_status

13. Cable duct  radius – 2 to 3 mm Modify shape of C – supports  2.5 mm4
Cable duct  radius – 2 to 3 mm
Modify shape of C – supports  2.5 mm
adapt new manifold to 1)
2/22/2019
DC_status

14. Calibration methods
lab aquarium ( DRS + cables for 2 DC)
Mn54 triggered ( 5.9 keV,835 keV photo peak)
Sr90 triggered (< 2 MeV b)
Cosmic m triggered
Lab support ( DRS + cables for 2 DC) (check all channels correctly connected and correlated anode up, anode down, cathodes)
Mn54 triggered (for the temporarily outer DC)
Sr90 not triggered
Cosmic m (triggered ? , complicated)
COBRA (not closed) (check all channels correctly connected and correlated anode up, anode down, cathodes) DC
NaI DC
2/22/2019
DC_status

15. Tokio
Scintillators
Cosmic m
COBRA Xe
NaI DC
2/22/2019
DC_status

16. Schedule beginning 2007 Cathode + Hood Anode ( new prints)
Feb 01
Feb 02
Mar 1
Mar 2
Apr 01
Apr 02
Mai 01
Mai 02
Jun 01
Jun 02
Jul 01
Cathode + Hood
4 weeks
Anode ( new prints)
12 weeks
construction
13 weeks
(Tightness)
Lab test
Sr90,Mn54,cosmic, all triggered
mount on support
test on support
(Sr90 ,self trigger, Mn54 trigger)
(triggered cosmic m’s ’ ?)
mount in Cobra
test in COBRA
(Sr90 for ,self trigger)
(triggered cosmic m ‘s ?)
„N bag“
2/22/2019
DC_status

17. New anodes  largest time consumer (production rate known)
Adapt to N bag conditions, New manifolds in optimized position
New hood and cathode frame : Andrei and Nicolai  mostly done
Replace anodes on DC04 t0 DC11, construct 8(10) new DC
LV+HV cable labeling + mount:
Test in aquarium with gas regulation, mount and test on support of modified and new DC
Transport, and insert of support with 16 DC and TC+N bag in COBRA
Test cabling in COBRA
2/22/2019
DC_status

18. 2/22/2019
DC_status