Observe c. 2mV p to p noise with DSO ( Z_in = 50 Ohm ) c. 60us period with HF structure. DSO connected to junction box via 34-way IDC - 16x Lemo-00 adaptor.

Origin of noise upstream of 4x34-way to 8x16-way Junction Box. Not microphonics from Edwards RV5 Rotary Pump.
No change observed with simple ground connections between NIM bin/+/-15V PSU/Junction Box and MSL type W1 preamplifier units/vacuum chamber/support assembly.


Estimate of electronic noise

Pulser BNC PB-5

Amplitude 0.5V
Attenuation x1
Decay time 1ms
Frequency 50Hz

Preamplifier RAL108
Output impedance 100 Ohm
Sensitivity 20mV/MeV ( into high Z load ), 6.7mV/MeV ( into 50 Ohm load ) 

Amplifier EG&G Ortec 571
Input terminated by 50 Ohm
Gain x1 (internal) x 1.0 (fine gain) x 50 (coarse gain ) = 50
Shaping time 0.5us

MCA Amptek 8000D
Input FSR 10V
12 bit ADC


Nominal gain = 6.7mV/MeV x 50 = 335mV/MeV

12 bit ADC input FSR = 10V / 0.335V/MeV = 29.85MeV FSR or 7.3keV/channel


dE p+n junction strip # 4 ( of 0-15 )

pulser peak centroid = 799.8 ch
pulser peak width = 7.8 ch FWHM = 57 keV FWHM


E p+n junction strip # 4 ( of 0-15 )

pulser peak centroid = 864.8ch
pulser peak width = 3.5 ch FWHM = 26 keV FWHM


E n+n Ohmic strip # 4 ( of 0-15 )

pulser peak centroid = 913.0 ch
pulser peak width = 5.3 ch FWHM = 39 keV FWHM


Noise estimates are probably accurate to c. 10% level.

Check RAL108 +/-15V PSU

Measured output voltages +15.21V -15.18V - OK

Observe output voltages with DSO ( ch #1 AC/1M +15V, ch #2 AC/1M -15V ) - see attachments 1 & 2

What we should observe is c. 1mV rms ( white ) noise but we clearly observe similar noise transients ( c. 60us period with HF structure ) to those observed at RAL108 
outputs. The RAL108 preamplifier units do have RC filters on the +/-15V - typically c. 100 Ohm and 4.7uF. Some additional, inline filtering with a lower rolloff 
frequency may be required.

> 
> Observe c. 2mV p to p noise with DSO ( Z_in = 50 Ohm ) c. 60us period with HF structure. DSO connected to junction box via 34-way IDC - 16x Lemo-00 adaptor.
> 
> Origin of noise upstream of 4x34-way to 8x16-way Junction Box. Not microphonics from Edwards RV5 Rotary Pump.
> No change observed with simple ground connections between NIM bin/+/-15V PSU/Junction Box and MSL type W1 preamplifier units/vacuum chamber/support assembly.
> 
> 
> Estimate of electronic noise
> 
> Pulser BNC PB-5
> 
> Amplitude 0.5V
> Attenuation x1
> Decay time 1ms
> Frequency 50Hz
> 
> Preamplifier RAL108
> Output impedance 100 Ohm
> Sensitivity 20mV/MeV ( into high Z load ), 6.7mV/MeV ( into 50 Ohm load ) 
> 
> Amplifier EG&G Ortec 571
> Input terminated by 50 Ohm
> Gain x1 (internal) x 1.0 (fine gain) x 50 (coarse gain ) = 50
> Shaping time 0.5us
> 
> MCA Amptek 8000D
> Input FSR 10V
> 12 bit ADC
> 
> 
> Nominal gain = 6.7mV/MeV x 50 = 335mV/MeV
> 
> 12 bit ADC input FSR = 10V / 0.335V/MeV = 29.85MeV FSR or 7.3keV/channel
> 
> 
> dE p+n junction strip # 4 ( of 0-15 )
> 
> pulser peak centroid = 799.8 ch
> pulser peak width = 7.8 ch FWHM = 57 keV FWHM
> 
> 
> E p+n junction strip # 4 ( of 0-15 )
> 
> pulser peak centroid = 864.8ch
> pulser peak width = 3.5 ch FWHM = 26 keV FWHM
> 
> 
> E n+n Ohmic strip # 4 ( of 0-15 )
> 
> pulser peak centroid = 913.0 ch
> pulser peak width = 5.3 ch FWHM = 39 keV FWHM
> 
> 
> Noise estimates are probably accurate to c. 10% level.

On the morning of Monday 14 August 2x RAL108 +/-15V PSUs were borrowed from the Edinburgh equipment in the ISOLDE hall to check whether the same transient 
noise is observed at the +/-15V PSU outputs.


PSU #2 Farnell MX2

Setup - attachment 1

DSO ch#1 +15V AC/1M, ch#2 -15V AC/1M - y: 50mV/div x: 1us, 500ns, 250ns & 25us/div - attachments 2-5



PSU #1 Coutant HSC15-3.0

Setup - attachment 6

DSO ch#1 +15V AC/1M, ch#2 -15V AC/1M - y: 50mV/div x: 25us/div - attachment 7


Conclusion

Observe same amplitude and HF structure with all 3x RAL108 +/-15V PSUs

08.35 Vacuum chamber pressure OK - see attachment 1

MSL type W1(SS)-20

3186-9  20um Depletion voltage 3V Operating voltage 6V
3585-12 20um Depletion voltage 2V Operating voltage 4V

MSL type W1(DS)-150

3458-1 157um Depletion voltage 22V Operating voltage 52V
3458-4 144um Depletion voltage 18V Operating voltage 48V

This morning 2x RAL108 +/-15V PSUs were borrowed from the Edinburgh equipment in the ISOLDE hall to check whether the same transient noise is observed at the +/-15V PSU 
outputs - this was confirmed. See https://elog.ph.ed.ac.uk/nToF/63

Following this test the same 2x RAL108 +/-15V PSUs were tested in the ISOLDE hall ( 19" rack adjacent to the HIE-ISOLDE GP scattering chamber ). 


PSU #1 Coutant HSC15-3.0

Setup and PSU details - attachments 1-4

DSO ch#1 +15V AC/1M, ch#2 -15V AC/1M - y: 5mV/div x: 400ns, 4us & 40us/div - attachments 5-7


PSU #2 Farnell MX2

Setup and PSU details - attachments 8-10

DSO ch#1 +15V AC/1M, ch#2 -15V AC/1M - y: 5mV/div x: 400ns, 4us & 40us/div - attachments 11-13


Conclusion 

The noise of the 2x RAL108 +/-15V PSUs differed somewhat ( frequency and structure of HF transients ) from each other in the ISOLDE test.

Compared to the EAR2, n_TOF test the amplitudes were c. 10x smaller and the HF transient frequency and structure differed.

This appears to confirm that the primary problem is the ac mains power in EAR2, n_TOF - input and/or output filtering is required.

PSU Calex

Setup and PSU details - attachments 1-3

DSO ch#1 +15V AC/1M, ch#2 -15V AC/1M - y: 20mV/div x: 100ns, 200ns, 1us, 2us, 10us, 20us & 100us/div - attachments 4-10

PSU Calex

Setup, PSU and ac mains filter - attachments 1-3


DSO ch#1 +15V AC/1M, ch#2 -15V AC/1M - y: 50mV/div x: 100ns, 200ns, 1us, 2us, 10us/div

Without ac mains filter - attachments 4-8



DSO ch#1 +15V AC/1M, ch#2 -15V AC/1M - y: 10mV/div x: 100ns, 200ns, 1us, 2us, 10us/div

With ac mains filter - attachments 9-13

Conclusion - Claud Lyons Ltd STF Series Surge & Transient Power Filter produces c. x 2 attenuation of HF noise transients

Neutron beam profile - film exposure overnight 12/13.9.24

The 2x sets of 34-way IDC to 37-way D connctor ribbon cables used at GSI for the two-alpha decay measurement have been located - see attachments 1-4.

They have been packed for shipment to CERN and delivered to stores for shipment. Awaiting quotation and P&M PO.

 20 micron (see 2015-10-05_12.46.59.jpg for detailed information) and 500 micron detectors

Testing preamps using pulser through common wire to both sets of preamps (see 2015-10-05_13.12.01.jpg).

64 x 14mA pos signals 15V
64 x 4mA neg signals 15V (see 2015-10-05_12.02.00.jpg for example on oscilloscope)

Sample has 105 microgram Li-6 (LiF - 95% enriched) 105 micron thick (2015-10-05_12.12.15.jpg is Li-6 side up, 2015-10-05_12.12.26.jpg is Li-6 side down... do not mix up!)

dE uses 22, 23 on ribbon connector, E 24, 25
dE from bias supply 2, E from bias 1

de and E pos signals needed to be inverted using jumpers. de negs not used, only 16ch (see 2015-10-05_14.59.12.jpg)

de first and last (0,15) are noisy- don't use. E detector ch 0 doesn't work.
Channels used dE 4-9, E(pos) 3-7 and E(neg) 3-7 (see 2015-10-05_15.11.37.jpg and 2015-10-05_15.11.44.jpg)

600mV in 50ohm coax with 25 hz pulser (positive signal) - see 2015-10-05_15.19.54.jpg and 2015-10-05_15.22.46.jpg

Leakage currents on detectors:

In air
10v: 0.03 micro amp det 1 leakage -dE
132v: 0.47micro amp det 2 leakage- E det

In vacuum
DE 0.04 micro amp
E 0.46 micro amp

Same size of signal at ADC hence 50 ohms coaxial.

The following channel explanations refer to cables at control area (not vault) see (2015-10-05_15.19.54.jpg) for full wiring information.

dE det= DEED 0 to -2V full scale, Lower limit 1800mV, Threshold 0V, thresh neg, pre 1024, post 2048, 20ms window, sample rate 225 MS/s
- L6D6 A = de 4
- L6D6 B = de 5
- L6D6 C = de 6
- L6D6 D = de 7
- LaBr 3 = de 8
- 21 = de 9

E det front= EFED 0 to -2V full scale, Lower limit 1800mV, Threshold 0V, thresh neg, pre 1024, post 2048, 20ms window, sample rate 225 MS/s
- 10 = Ef 3
- 12 = Ef 4
- 13 = Ef 5
- 14 = Ef 6
- 15 = Ef 7

E det back= EBED 0 to +2V full scale, Lower limit -200mV, Threshold 0V, thresh pos, pre 1024, post 2048, 20ms window, sample rate 225 MS/s (except EBED 5,6,7 which MUST be 900MS/s due to beam pick up signal)
- 16 = Eb 3
- 18 = Eb 4
- 20 = Eb 5
- 38 = Eb 6
- 40 = Eb 7

Run number 203385 on https://project-ntof.web.cern.ch/project-ntof/eRunbookEAR2.php

Fairly self explanatory, note that images with time-stamps before 13.08.29 were taken before fitting the o-ring on the flange and therefore lateral positions will be different to photos after 13.08.29. Individual detector heights were not changed.

 Note that detailed DAQ information available from project-ntof.cern.ch erunbook ear2.

As a rough guide: 6/7 mV per MeV

5mV thresh back side E, -5mV front E
-5mV dE
Implemented from Run 203388

From Run 203389
-7mV in Deed 8&9, EFED
+7mV in EBED

Run 203390
Thresholds back to -6mV for deed 8&9

Gamma flash ends at 70micro sec, corresponds to neutron energy of ~200keV...

 Leakage tues am
0.03 microA dE
0.52 microA E

Before leaving at 11.30am or so-
Bias dE up to 20V, leakage to 0.07microA
E has 0.51 microA

Problem solving dE signals...
SIG l6d6 a has signal of 600mV
SIG 24 has signal of 500mV
White noise is comparable, but transient ringing on l6d6 could indicate higher capacitance

Testing dE for signal with alpha source- but removed before continuing run.
dE sees particles after rotating ribbon by 180 degrees (abnormal detector)

External pulser triggering (2015-10-06_11.30.jpg )
Pulsar trigger, +2.5V external from proton pulse (10ms before beam), lasts 1ms (width).

Convert pulse input from TTL to NIM to go into delay (15ms).
Start delay in dual timer, then output to trigger pulser (TTL)

 Pulser out of 5,6,7 EFED- extended to 32ms

Changed full scale on ADC to 0.2V,
Offset changed by factor of 10.
Zero suppression on, de -3mV thresh
E +-5mV thresh
Post sample 4096

5pm increased post sample for spd-02886 to 8192 as higher sample rate due to pick up.

Corrected EBED 4 offset.

(Again, all DAQ settings also recorded to the nToF erunbook)

Changed pulser to 13ms.

Alpha source in - containing 148Gd, 241Am, 239Pu, 244Cm (4x 1kBq)

Leakage on arrival
dE 0.08microA , 19V
E 0.48microA 132V

At leaving
dE 0.08 micro A
E 0.41 micro A

Pulser to 20ms (2015-10-07_13.58.08.jpg)

DAQ:

EBED 5,6,7 have post sample 16382
Increased further at 4pm - 16000+ post sample for 225 samples

 

Removed source and removed Li sample for blank frame test

Leakage
DE 0.06micro A
E 0.41 micro A

DAQ 
56.25 sample rate all except EBED 5,6,7

 Leakage before take down:
de 0.07 micro A
E 0.47 micro A