B. Vallage (26/3/2014) I have no fundamental remarks, only a minor point which is incorrect and should be modified as follows

- I propose to rewrite the sentence on line 68-70 as: "The threshold crossing time and time over threshold (ToT) are digitized by a on-board ns precision time stamping implemented in the readout FPGA (ref 14)."

- the reference cannot be the paper of A. Zwart et al (13), since it has nothing to do (different time resolution, data format, number of channels) with the implementation in the PPM-DOM and PPM-DU which is described in reference S. Anvar et al (14).
- I also propose to modify lines 74 and 75 as follows: "The data are transported to the 45 km distant shore station through the ANTARES Gb/s multiplexed optical link." I removed the 2 references, since (14) describes the DOM readout already referenced for the time stamping in line 68-70, and (15) which describe the ANTARES readout which is on purpose completely independent of the DOM readout (different GPS, clock, network, bootserver, acquisition PCs, etc).

- line 137: it should be “Figure 3C”(not 3B).

- line 193: I think “get less” should be replaced by “decrease” (even if the following sentence begins with “The decrease”)

- line 263: I think “continues to the present” should be replaced by “is still going on”

l.26: IceCube collaboration  IceCube (Antarctic) collaboration

l.56,57: diameter, housing  diameter, as pressure case housing

l.57: tubes with  tubes ‘PMTs’ with

Figure 2: lettering of axis-labels should be bigger

Figure 2B: the red line is barely visible: please thicken

caption Fig. 2,l.1: Rate  Hit rates (to be equal to naming in Figure-axis-legend)

caption Fig.2,l.1: ToT  ToT (see text)

caption Fig.2,l.1: long  broad

caption Fig.2,l.4: fit of  fit (red line) of

l.58: mm [1] mm (about 3") [1]

l.60,61: photomultiplier tubes (PMTs)  PMTs

l.78: single sphere  single glass sphere

l.93: site (  site south of Toulon, F (

l.98: define ‘runs’ (?)

l.101: registered ToT  registered hits as a function of ToT

l.104: ns at FWHM  ns FWHM

l.105: ToT caused  ToT broad-peaking around 240 ns caused

l.117: baseline corresponds  baseline of about 250 kHz corresponds

l.128,129: What is meant by this sentence, peaks due to bioluminescence? Please clarify.

Figure 3: Data do not seem to be binned in ~100 ms bins. The variability is much faster than that of the (100 ms) tick-marks. Lettering in insert of A is too small; Y-axis caption of A should read ‘Hits’ for consistency; x-axis of A is ugly, numbers make one long row (decrease lettering?);make z-axis of C longer (or reduce number of ticks); z-axis legend of C is missing; y-axis legend of C should be bigger and not overwrite numbers; Please also indicate far end of y-axis of C (+/- 180°?); Please also indicate far end of x-axis of C (40° ?)

Caption Fig.3,l.1: Rates  Hit rates

Caption Fig.3,l.2: why use ‘~’ before 100 ms ? in the text this is not done. What is the exact value?

Caption Fig.3,l.2: hits while  hits summed over all 31 PMTs while

Caption Fig.3,l.9: zenith.  zenith angles. What is the large value at φ~180°, θ~60°?

Figure 4: Lettering of axes A-D too small

l.137: 3B  3C

l.140: activity is  activity, excitated upon collision of animals mainly advected by currents, is

Figure 5, all y-axis captions: Rate  Hits

Caption Fig.5,l.1: Rates  Sum over all PMTs of hit rates

l.186: mean  total

l.187,188: minutes  min

l.187,188: Figure 5 displays Run nr. 720-1060, which is about 2.2 days of data, not six months.

l.191: full  total

l.194: biolluminescent  bioluminescent

l.194,195: I absolutely do not see a variation from summer through winter in the decrease of levels in Fig. 5A-C!

l.196: instantanious  instantaneous

l.199: This  These

l.204,205: stable.  stable and no bursts due to bioluminescent flashing are observed.

Figure 6: Is there is a specific reason to choose 25h 35 min of data?; Rate  Hits ; Lettering of inserts is too small; x-axis of B cannot exist of just one number

Caption Fig.6,l.5,6: centre of the PMT  centre of the DOM (?)

Caption Fig.6,l.10: cylinder.  cylinder.)

l.218: rate is  rate (coincidence level of 1) is

l.235: I don’t understand ‘three twofold coincidences’, but that may be just me.

l.247: (…but perhaps other shadowing effects??)

l.249: phototubes  PMTs

l.251: horizonrally  horizontally

l.256: phototubes  PMTs

l.258: telescope at a depth of around  telescope around

l.262: minutes  min

l.266: activity. The  activity. This supports earlier findings [20,21] that most intense deep-sea bioluminescence is caused by fishes and zooplankton, not by (omnidirectional) bacterial glow. The

l.285: Detector,Science  Detector, Science

l.294: strange characters before ‘-rays’

l.299: Astrophysical Journal  Astrophys. J.

l.302,303: Astrophysical Journal  Astrophys. J.

l.305: The  the

l.305,306: Instr. and Methods  Instr. Meth.

l.313: (KM3NeT  (on behalf of the KM3NeT

l.305,306: Instr. and Methods  Instr. Meth.

l.314,315: Instr. and Methods  Instr. Meth.

l.322: Instr. and Methods  Instr. Meth.

l.324: Instrum. and Methods  Instr. Meth.

l.327: Calibration  calibration

l.331: Instr. and Methods  Instr. Meth.

20. I. G. Priede et al.; The potential influence of bioluminescence from marine animals on a deep-sea underwater neutrino telescope array in the Mediterranean sea, Deep-Sea Res. I 55,1474 (2008)

21. H. van Haren et al. (ANTARES-collaboration); Acoustic and optical variations during rapid downward motion episodes in the deep north-western Mediterranean Sea, Deep-Sea Res. I 58, 875 (2011)

thanks for the paper draft of the KM3NeT PPM DOM, which contains very

good results and shows that the multiPMT idea is working nicely.

My comments are included in the annotated pdf file which can be

retrieved by following the instructions below.

Some of you may have received my previous mail with the file attached,

from others I received failure messages, therefore I send the file here

again.
with best regards,

        Herbert
Right click on the following URL and

* choose "Save Target As" (Outlook Express)

* choose "Save Link Target" (Thunderbird)

or start your browser and copy and paste the complete URL in the address

or location box.
url     : http://bars.rug.nl/download/4e70133622df7a9a

filename: PPMDOM-v11.1-HL.pdf

filesize: 8.4MB

available until: 2014-04-14

30: prime  additional

48: KM3NeT predecessor ANTARES [9].  KM3NeT predecessors NESTOR [xxx] and ANTARES [9].

[xxx] G. Aggouras et al., A measurement of the cosmic-ray muon flux with a module of the NESTOR neutrino telescope, Astroparticle Physics, Vol 23, 377-392, 2005

52: line during deployment line and deployed

54: ANTARES detector [10].  ANTARES detector [10] and data have been already recorded.

58: by a reflector  by a cone-shaped reflector

93: 42° 50 N, 6° 10 E  42° 50’ N, 6° 10’ E

147: by a factor 2.5. To select a  by a factor 2.5. ¶To select a

194: biolluminescent  bioluminescent

255: The new design optical module The new optical module designed
GRAPHS

fig 2. Y axis scale confuses me. We have a rate of 50000 hits per ns??

And I suppose that in the x axis it should be: ToT [ns] instead of ToT/ns

Fig3a: Rate [ns] instead of Rate / ns

SAME CORRECTION TO ALL FIGURES (except 4E, 5, 6A; they are correct)
fig 3A: labels of x axis could be clearly separated
fig3 legend: measured in 100 ns bins.  measured in 100 ns timeframe bins.

-> Neutrino detection is based on sampling the Cherenkov light

-> Sampling Cerenkov light in 

-> Digital Optical Module Design 

Reference 13 should be maintained but reference 14 should appear right beside it.

It would be nice to mention that the TDC has nano second resolution and 31 synchronized channels.
75 - Reference 15 doesn't seem fit.

To the best of my knowledge, the DOM is completely separated from ANTARES in terms of data flow.

Adding reference 15 makes it ambiguous so it should be removed.
My feeling is that a sentence somewhat like "A more detailled description of the 

DOM electronics and Data acquisition system is given in reference [14]." 

96 - commenced 

-> began, started ..
106 - "the distribution of the time difference between successive hits .."

-> distribution of time intervals between successive hits

-> with a slope \tau

-> rate around

-> Because of its low 1KHz repetition frequency, the signasl from ..

-> it is 2.5 times higher

Isn't this the rigth place for a new paragraph ?

Figure 5 : it would look nicer if all the plots had the same range on the horizontal axes.

159 - "in the water."

in the surrounding water 
165 - the reason is that DOM

Missing article.

where plots A to D show the rates for 

as a function of run number.

There must be a way to say this better !

Bioluminescent

instantaneous

199 - This curve thus show

-> These plots thus show ..

-> It is expected to be completely stable ...

red dots in 5C gathering along two alomst three nearly horizontal lines ?

-> incorporating the / accounting for that effect ...

-> The new optical module design 

-> in deep sea.

-> connected and is still going on.

-> intra DOM timing only. I suppose the array will need more than K40 decay 

for synchronization and timing calibration.

Don't forget the ANTARES acknowledgement

       Collaboration with capital 'C'

L38...the Cherenkov light is induced by the passage of the muon, not emitted by the muon

Fig. 1. I attached to this mail a photoshoped version of my photo, in which the cable is removed

FIg 2b....there is a red area on the data points which is not referred to. Remove it or state that the exponential fit was made on this region

L83...this is a nice opportunity to emphasize ALL the advantages of the multiPMT design...

i.e. directional information, better for ageing, availability of PMTs, cost reduction, less leak points.

Section 4....I think I would explained the K40 origin of the light much earlier than currently.

It is already needed to understand Fig 2, otherwise the reader may think it is all due to dark current.

I would also state early on the typical dark count of the PMTs (with no light at all).

Fig 3a...the blue curve, seem to have something yellow 1/3rd of the way along?

L135...quote the value of the high rate veto cut (8.5kHz?).

Fig 4....strange having dotted error bars

L137...3C

L147...presumably due to impacts of organisms on the structure or stress induced by turbulence around the structure

L148...keep to the impersonal tense (no 'we')

L186...205/FIg 5....not sure I really grasp what is the extra information from all this discussion that has not already been

discussed in the previous plots. It is good to show the DOM has operated for a long period. I expect the variation will

correlate well with the value of the sea current during the run.

L202...how do I see this?

L207..209....remove,  this is obvious

L231...intensity-->rate