Calliope facility @ ENEA Casaccia

• MON = monitor MWPC (CH1)

• T1 = test MWPC (CH3)

•T2 = test MWPC (BTF,CERN1,CERN2)

• T = temperature sensor

• P = atmospheric pressure sensor

• gas mixture: Ar / CO2 /CF4 = 40 / 40 / 20

• gas flow ~ 6 l/hr = 100 cc/min (1 volume in 20 min)

• Source Co60 (~25,000 curie)

MON

T2

GEM

PC

Co60

BO

TT

LE

S

HV

CONTROLROOM

4.5

m

P

T

win

dow

T1

GA

S

RA

CK

CERN chambers

• CERN1: in Closed loop Active area ~ 875 cm2

(B 1.5 mm pitch, others 2 mm) B=reference (every day ON 2-3 hrs) Total Wire length ~ 4300 cm I ~ 990 A/gapHV( A, C, D) ~ 2.65 kV HV(B) ~ 3 kV

• CERN2: in Open Mode Active area ~ 480 cm2

(all gaps 1.5 mm pitch) C=reference (every day ON 2-3 hrs) Total Wire length ~ 3200 cm I ~ 670 A/gapHV( A) ~ 3.14 kV HV(B) ~ 3.115 kVHV(C) ~ +-2.125 kV HV(D) ~ +-2.15 kVGaps C,D are asymmetric (wire is at 3.65 and 1.35 mm from cathode)

MWPC-LNF chambers

• CH1 = MONITOR CHAMBER (1.5 mm pitch) active area 500 cm2

Total Wire length ~ 3330 cm I ~ 20 A/gapGaps A,B in OPEN Mode; Gaps C,D in Closed Loop.

• CH3 = TEST CHAMBER 1 (1.5 mm pitch) active area 500 cm2

HV=3.2 kV (reference A ON for ~5 hrs every 2-3 days)Total Wire length ~ 3330 cm I ~ 160 A/gapGaps A, B, C, D in Closed Loop.

• BTF = TEST CHAMBER 2 (2 mm pitch) active area 1200 cm2

HV=2.75 kV (reference D ON for ~5 hrs every 2-3 days)Total Wire length ~ 6030 cm I ~ 1200-1500 A/gapGaps A, B, C, D in OPEN Mode.

Layout of chamber positions and gas

MWPC-CH3 MWPC-BTF GEM-LNF-TEST1

GEM-LNF-TEST2

GEM-CA-TEST1

GEM-LNF-MONIT

MWPC-CH1

MWPC-CH1

P1 P2 0.1-0.2 Gy/hr

P3 0.3-0.6 Gy/hr

P4 10-20 Gy/hr

GEM-CA-TEST2

MWPC-CERN1

MWPC-CERN2

3 m rack

Closed loop Open mode GEM (open mode)

AB

CD

position

Atmospheric pressure vs. Time

Temperature of source room vs. Time

Gas system

One bottle for each gas (Ar, CO2,CF4)Gas from bottle to Mass flowmeter (connected to MKS)Total gas flow: 40/40/20 cc/min = 6 l/hr to mixer (little cylinder)Typical flows:

• Open Mode ~ 5-6 l/hr• Closed loop: fresh gas ~ 1.35 l/hr circulating gas ~ 6.5 l/hr

Fresh gas should be 10% of circulating gas, but below the 20%(i.e. 1.35 l/hr) the system is unstable.

First purifier used from 16/6 to 3/7 (~ 17 days). May be too long ?Third purifier (asked 24th june) arrived only on July 9th !!!!!! Content of O2 was measured and did not change, but water content isunknown.The oil in the Open Mode bubbler is dark brown, while it’s clean for the Closed loop (this is not sufficient to state that purifier is working properly).

Saturation of gas gain

HV % Sat. HV % Sat. HV % Sat.

A 3.2 9 2.75 7

B 3.2 33.3 3.15 7 2.75 6

C 3.2 6.3 3.2 8.3

D 3.2 31.4 3.2 9.9 2.75 8

CH3 CH3 w/o Resis. BTF

Saturation < 10 %

Currents in BTF gaps (open mode)

Currents in BTF reference gap D

Currents in BTF reference gap D

Ratio of currents BTF(A,B,C)/D

Currents in CH1 gaps A,B (open mode)

Ratios of currents BTF(A,B,C)/CH1(A+B)

Currents in CH3 gaps (closed loop)

Currents in CH3 gaps (closed loop)

Currents in CH3 reference gap A

Currents in CH1 gaps C,D (closed loop)

Ratios of currents CH3(B,C,D)/CH1(C)

Ratios of currents CH3(B,C,D)/CH3(A)

Integrated charges

M1 M2 M3 M4 M5R1 1,21 0,20 0,05 0,07 0,05R2 0,49 0,14 0,02 0,02 0,02R3 0,21 0,07 0,01 0,01 0,01R4 0,07 0,01 0,00 0,00 0,00

C/cm (TDR with safety factors, 1.5mm pitch, 0.88 pC/hit)Q x 0.5 in M1-M2M3R1R2 (symm cathode), x 2 in M2-M5 (due to photons)Q=0.88 pC/hit is considered to be measured at relativistic rise (10 GeV)(if not, extra factor on M1 should be added) L=2 x 10**32

M1 M2 M3 M4 M5R1 1,619 0,264 0,070 0,092 0,062R2 0,655 0,187 0,023 0,031 0,025R3 0,282 0,092 0,014 0,011 0,009R4 0,088 0,017 0,006 0,004 0,003

Same as above, but for 2 mm pitch.

Dark currents (first measurement: 16-jun)

ON OFF ON OFF ON OFF

A 21.4 0.6 112 0.4 1300 0.8

B 19.6 0.2 135 1.0 1480 0.6

C 27.2 1.0 141 0.6 1280 0.6

D 29.2 8.2 127 0.6 1110 0.2

CH1 CH3 BTF

CH1 (C,D) 3.15 3.05 kV CH3 (B) 3.2 3.15 kVThe power supply does not allow to measure currents < 1 uA

Dark currents (second measurement: 26-jun)

SY2527 N471A

(nA)

SY2527 N471A

(nA)

SY2527 N471A

(nA)

A 0.8 0 28.8 5 @ 3.2 0.6 70

B 0.2 0 0.4 9 0.4 70

C 13.2 0 @ 3.3 kV 0.2 9 0.2 38

D 5.6 1200@ 3.15

0.2 7 0.4 28

CH1 CH3 BTF

To read currents with N471A we need to switch OFF/ON all gaps CH1 (D) draws current also after switch offAll BTF’s decreasing (for ex. BTF(D) 90 28 nA in ~ 1 hr)

Integrated charge in CH3

Integrated charge in BTF

Currents in CERN1 (closed loop)

Currents in CERN 2 (open mode)

CERN 1 ratiosCERN 1 I(A,C,D)/B(ref)

0,92

0,94

0,96

0,98

1

1,02

1,04

0 5 10 15 20 25

Days

A.U.

Series1

Series2

Series3

CERN 2 ratiosCERN 2 I(A,B,D)/C(ref)

0,8

0,9

1

1,1

1,2

1,3

0 5 10 15 20 25

Days

A.U

.

Series1

Series2

Series3

I_ref (closed) / I_ref(open)Ratio reference gaps I(D1)/I(C2)

1,3

1,4

1,5

1,6

1,7

1,8

1,9

0 5 10 15 20 25

Days

A.U.

Integrated charges in CERN 1

Integrated charges in CERN 2

Conclusions

MWPC-LNF• Integrated charges: BTF (2 mm) 300-370 mC/cm (> M1R3) CH3 (1.5 mm) 80-90 mC/cm (>M2R3)• No aging in Open Mode chamber (within ~5%)• Analysis of Closed loop chamber requires more work

MWPC-CERN• Integrated charges: CERN 1 (2 mm) ~340 mC/cm (> M1R3) CERN 2 (1.5 mm) 300-390 mC/cm (>>M2R3)• No aging in both chambers (within ~8%)

Several problems with gas mixture: • low CO2 content for ~ 10 days ?)• Lower currents in all chambers after change of CO2 bottle• Undefined purity of mixture and H2O content

More time for an accurate data analysis, especially for closed loop

Spare transparencies follow

Source pool

windowirradiated panels

TEST CHAMBER 2

MONITOR CHAMBER

MON

TEST

GEM

PC

Co60

BO

TT

LE

S

HV

CONTROLROOM

4.5

m

MWPC prototypes

Test chamber 1 and monitor chamber :

• chambers are 4-gaps with active area ~ 251 x 208 mm2

• wire pitch 1.5 mm (8 pads x 17 wires)

• Operating voltage = 3200 V

• Typical currents: test ~ 160 A/gap monitor ~ 20 A/gap

Dose rates (still to be measured)

• CH1 dose rate < 0.025 Gray/hr

• CH3 dose rate ~ 0.1 – 0.2 Gray/hr (~0.3 A/cm2)

• BTF, CERN1, CERN 2 dose rate ~ 0.3 – 0.6 Gray/hr (~1 A/cm2)