Vgun update

Late April: VGun rebuilt with top cesiator

Commission with a bulk wafer: beam (May 9)

Mott checkout and commission: polarization

LL bake with strained layer (May 23), M5-6383, chip #3

Activation+HV

# [Leak on the 2+3.4 double knife edge]{.underline}

Bake (May 29)

In parallel: send to Andy for imaging, M5-6383, chips #7 and #10

1.  **NOVO, June 4, M5-6383, chip#2, USUAL, low P (hydro 2)**

Activation: QE=0.6% at 840 nm

Reactivation (June 12), mini spin-dance

Pe= 62% at 840 nm, 76% at 860 nm, very uniform (June 19)

> Hydrogen cleaned, no bias (June 23), Pabs\~ 30 to 50W, for 80 minutes

Reloaded into VGun, activation: QE=0.5% at 840 nm

Broken wafer but good scan

Measured \~10% depolarization (June 27)

12 hours heat cycle at 675 C, activation, Mott: polarization not
restored (July 1)

2.  **Si, 07-11, M5-6382, chip #9**

> New stalk-\> bad
>
> Broken wafer, but good scan, good QE
>
> HV fried

3.  **Si2, 07-16, M5-6382, chip #7**

> Old stalk #2
>
> Broken wafer, but good scan
>
> Storm, 2 bakes

## Found leaky Load Lock valve

Diode effect: 2000 V

# [Leak on the 2+3.4 double knife edge]{.underline}

Fix leak, reheat, activate: OK QE

Pe=75% at 870 nm

HV fried

4.  **Si3, 07-28, M5-6749, chip #9, ION ENHANCED, high P (hydro 3')**

Old stalk #1

Jack screws for stalk alignment-\>Unbroken wafer the 1^st^ time, then it
broke

Diode effect: 2800 V

### Leaky vent port

Bad scan-\> optics cleanup and realignment

Reactivation: QE=0.35% at 840 nm, good scan

Pe=70% at 840nm, 78% at 870 nm (July 29)

> Hydrogen cleaned with negative bias and (Aug 8), Pabs\~ 20 to 40 W

Reloaded into VGun, activation: QE=0.35% at 840 nm\`

Measured \~15% depolarization (Aug 14)

5.  **Birsk, 08-15, M5-6383, chip #4, ION REDUCED, low P (hydro 4)**

Old stalk #2

Jack screws to align-\>Unbroken wafer during insertion, broken as rested
on electrode

Activation: QE=0.7% at 840 nm

Diode effect: 1500 V

Pe=60% at 840 nm, 76% at 870 nm (Aug 21)

> Hydrogen cleaned with positive bias (Aug 26), Pabs\~ 20 to 40 W

Reloaded into VGun, activation: QE=0.6% at 840 nm

Diode effect: 1500 V

Good scan, but missing chunk of wafer

Measured \~10% depolarization (Aug 29)

6.  **Hope, 09-5, M5-6383, chip #9, ION ENHANCED, low P (hydro 3)**

#### [DISREGARD HOPE RESULTS FOR PAPER]{.mark}

Old stalk #1

Jack screws to align-\>Unbroken wafer

Activation: QE=0.6% at 840 nm

Diode effect: 1500 V

Pe=65% at 840 nm, 78% at 870 nm (Sep 10)

Found systematic depolarization effect due to ND filter (09-11)

# [Leak found on the gun VAT valve]{.underline}

> Hydrogen cleaned with negative bias and (Sep 12), Pabs\~ 20 W

Reloaded into Vgun, activation: QE=0.45% at 840 nm

Diode effect:

Measured Pe at 3 locations before hurricane shutdown: \~20%
depolarization (Sep 16)

7.  **Tunnel test, 09-26, M5-6749, chip #3, anodized**

> Mounted on stalk #2, Indium without heat
>
> Hydrogen cleaned for 30 minutes (Sep 26), Pabs\~20 W
>
> Activation: QE\~0.15% at 840 nm after 2 hours at 675 C
>
> Re-activated after 2 more hours at 675 C: QE\~0.02%
>
> Hydrogen cleaned for 25 minutes (Oct 3), Pabs\~ 50-70 W
>
> Activation: QE\~0.1% at 840 nm after 2 hours at 675 C

8.  **SVT superlattice test, 10-07, SVT-4577, chip #3**

Mounted on stalk #2, Indium without heating

No hydrogen dose, not anodized

Activation: QE\~1% at 780 nm after 2 hours at 600 C / 520 C (Oct 9)

Pe\~80% at 780 nm, uniform

Analyzing power \~ 3% at 780 nm

Re-activation: QE\~1% at 780 nm after 2 hours at 630 C / 540 C (Oct 14)

Re-activation: QE\~0.9% at 780 nm after 15 min at 675 C / 580 C (Oct 21)

QE vs laser power dependence: -0.15%/mW

> Hydrogen cleaned for 30 minutes, Pabs\~20-40 W

Re-activation: QE\~0.5% at 780 nm after 2 hours at 630 C / 540 C (Oct
24)

QE vs laser power dependence: -0.21%/mW

Re-activation: QE\~0.5% at 780 nm after 2 hours at 630 C / 540 C (Oct
29)

QE vs laser power dependence: -0.23%/mW

Pe remains high after Hydrogen dose

> Hydrogen cleaned for 30 minutes (Nov 11), Pabs\~60-80 W

Re-activation: QE\~0.07% at 780 nm after 2 hours at 630 C / 540 C (Nov
12)

9.  **Maybe, 11-18, M5-6383, chip #6, anodized, ION ENHANCED, low P
    (hydro 5)**

Anodized by Marcy on 11-17, no hydrogen dose

Mounted on stalk #A, Indium, no heat in air

Activation: QE\~0.4% at 840 nm after 2 hours at 675 C / 580 C (Nov 19)

Pe\~76% at 870 nm, same as Novo

> Hydrogen cleaned for 80 minutes (Nov 24), Pabs\~75 W, -290 V on stalk

Re-activation: QE\~0.3% at 840 nm after 2 hours at 675 C / 580 C (Dec 2)

Measured Pe at 3 locations: \~20% depolarization (Dec 4)

10. **Rudolph, 12-5, SVT 4577, chip #2, anodized, USUAL, high P (hydro
    6)**

Anodized by Matt&Marcy on 12-4, no hydrogen dose

Mounted on stalk #2, Indium, no heat in air

Anode ring shorted to the 10" flange (12-8), activation in prep. chamber

Activation: QE\~0.8% at 780 nm after 2 hours at 600 C / 540 C (Dec 9)

Re-activation: QE\~0.8% at 780 nm after 2 hours at 630 C / 540 C (Dec
10)

Pe\~80% at 780 nm, same as unanodized SVT #8

Analyzing power \~ 3% at 780 nm (same as unanodized)

Stalk removed from vertical gun and loaded into portable H with glove
bag during gun rebuild.

# [Gun rebuild]{.underline}

New anode ring installed: larger and angle mount

Manual VAT valve replaced by new one

2 right angle valves replaced by new ones (top cross)

Cesiator strips replaced by used ones from bottom Cs (no more 1" strips
in stock)

Bake started with bulk wafer, interrupted by power loss and restarted
from there

11. **Test, 12-15, bulk wafer**

Unanodized bulk loaded before the gun bake to check gun conditions

Activation attempt: photocurrent overwhelmed by Cs ion current on the
ring (300 V) fixed by reducing the bias on the anode ring

QE\~1% at 780 nm

12. **Nougat, 01-15-04, SVT 4578 chip #3, unanodized**

Mounted on stalk #1, Indium, no heat in air

LL bake with very high pressure

Activation: QE=0.15% at 780 nm after 2 hours at 630 C

Re-activation: QE=0.6% at 780 nm after 2 hours at 630 C

13. **Gruyere, 01-27-04, SVT 4721 chip #3, unanodized, USUAL**

Mounted on stalk #3, Indium, no heat in air

Activation: QE=0.5% at 780 nm after 1.5 hours at 630 C (Jan 28)

Re-activation: QE=0.65% at 780 nm after 1.5 hours at 630 C (Jan 30)

Pe\~80% at 780 nm (uniform over 2 locations out of 3)

Hydrogen cleaned for 18 minutes (Feb 3), Pabs\~80 W

# [Leak found on the top 10" flange]{.underline}

Finish the LL bake after the leak was fixed (Feb 4)

Activation (weird): QE=0.04% at 780 nm after 2 hours at 630 C (Feb 5)

Re-activation: QE=0.08% at 780 nm after 2 hours at 630 C (Feb 6)

Pe\~70% at 780 nm (uniform over the 3 measured locations)

#### [DISREGARD HOPE RESULTS FOR PAPER]{.mark}

14. **Reblochon, 02-10-04, SVT 4722 chip #3, 5 mm Ta cup, USUAL**

Mounted on stalk #2, Indium, no heat in air

Used a 5 mm Ta cup newly polished by Jim to test field emission

Activation: QE=1.1% at 780 nm after 1.5 hours at 630 C (Feb 12)

Field emission \< 1 pA at 100 kV

Re-activation: QE=0.9% at 780 nm after 1 hour at 630 C (Feb 17)

Field emission \< 120 pA at 100 kV

Pe \~ 80% at 780 nm (with 6% of Mott counts due to FE)

Re-activation: QE=0.8% at 780 nm after 1 hour at 630 C (Feb 19)

Field emission \< 1 pA at 100 kV

Pe \~ 80% at 780 nm (no FE)

Added 50 min of Cs without heat cycle before, field emission \< 1 pA at
100 kV

Hydrogen cleaned for 6 minutes (Feb 24), Pabs\~90 W

Activation: QE=0.45% at 780 nm after 2 hours at 630 C (Feb 26)

Pe \~ 80% at 780 nm, with some FE, but non-measurable (Mar 2)

Hydrogen cleaned for 6 minutes (Mar 5), Pabs\~85 W

Activation: QE=0.3 to 0.6 % at 780 nm (undetermined) after 2 hrs at 630
C (Mar 8)

Re-activation: QE=0.3 % at 780 nm after 1 hour at 600 C (Mar 10)

Hydrogen cleaned for 18 minutes (Mar 12), Pabs\~75 W

Re-activation: QE=0.25 % at 780 nm after 2 hours at 630 C (Mar 22)

Depolarization \~ -5% , on 2 locations (Mar 24)

Re-activation: QE=0.3 % at 780 nm after 1 hour at 630 C (Mar 25)

Depolarization confirmed \~ -5% , on 3 locations (Mar 25)

15. **Brie, 03-30-04, SVT 4577, #6, 5 mm Ta cup, USUAL**

Mounted on stalk #4, Indium, no heat in air

Used a 5 mm Ta cup newly polished by Jim

Activation: QE=1.1 % at 780 nm after 2 hrs at 630 C (April 1)

Pe \~ 85% at 780 nm (April 2)

Hydrogen cleaned for 30 minutes (April 6), Pabs\~50 W

Activation: QE=0.3 % at 780 nm after 2 hrs at 630 C (April 7)

Pe \~ 77% at 780 nm (April 8)

Re-activation: QE=0.4 % at 780 nm after .75 hr at 630 C (May 5)

16. **Eclair, 05-15-04, Chalcopyrite CuInSe2, #134**

Mounted on stalk #4, Indium, no heat in air

Used a 9 mm Ta cup

It is the nicest samples from the ones given by A. Rockett #134, (100)

Heat cycle 1 hr at 650 C (May 21): QE\~0

Re-heat and activation: failed

> Re-activation: QE \~ 10^-4^% at 800 nm after 45 min at 550 C (May 25)
>
> Abandon the test, waiting on feedback from Angus

17. **Salut, 06-29-04, ST 6967, \# 9**

Mounted on stalk #??, Indium, no heat in air

Activation: QE\~1.2 % at 780 nm and \~ 0.35% at 850 nm after 2 hrs at
675 C (Jul 1)

Pe \~ 79% at 870 nm (Jul 2)

Re-activation: QE\~ 0.3% at 840 nm after 1 hr at 675 C (Jul 12)

Bad vacuum: discovered that the ion pump power supply was off

Pe \~ 79% at 870 nm (Jul 13)

##### NB: QE was not measured after the wafer was activated in a good vacuum 

18. **Ken's first sample, 09-10-04, SVT 5128, #5 or 6, As capped**

Mounted on stalk #??, Indium, no heat in air

Used a 5 mm Ta cup

Very slow heat cycle: \~ 4 hours to reach 610 C

> Bad activation, maybe because of equipment pb: QE\~0.1% at 780 nm (Sep
> 14) after a quick heat cycle (15 min at 500 C)

Re-activation: QE\~1 % at 780 nm (Sep 15) after heat cycle (1 hr at 620
C)

Pe \~ 81% at 780 nm (Sep 16)