Hier sind noch ein paar Bilder vom Ionenstrahl , wie er gestern Abend war.

• 10:50 I am trying to identify the issue.
  
• 14:00 I increased the current limit Iset to 500 uA and the PMT was working OK by an applied voltage of -2500 V. After few minutes the HV power supply showed again an alarm. Afterwards the HV power supply CH0 is not giving any voltage anymore :-/
  
• 14:15 We Danyal and me, tried to get the PMT working using an alternative power supply. By a voltage of -2500 V the PMT does not show any signal.
  
• 16:50 I tested the HV power supply (CH0). It is working again.
  

The readout of the HV divider runs on a RaspberryPi inside the HV-cave of the electron cooler.
Starting from 2025-02-27 09:42, the divider ratio was changed from 248517 to 248515. Usually, the
readout should run continuously. If not, the following procedure must be applied:

1. Connect to the Rasperry:
  ssh esr_cooler@140.181.95.195 (ask Konstantin for pwd)
2. Display logging screen:
  screen -R signals (Typically you can use arrow up)
3. Stop logging, if it is running:
  Option 1: Type "stop" and press enter.
  Option 2: control + C
4. Restart logging:
  "python main.py -i 0.1 -f loss_current -d 3 5"
5. Detach screen:
  control + a + d
6. Disconnect from Raspberry

Gestern Abend haben wir die Signal Laufzeiten im gemessen:

PMT Mitte: 1213 ns (bis zur Messhütte ohne DAQ sind es 1025 ns) 
PMT Nord: 1212 ns
PD Nord: 1171 ns (ohne DAQ sind es 1172 ns) 

Weil PD Nord zu kurz war und wir es mit einem Gate&Delay nur um >40 ns Sekunden verschieben konnten, was gerade nicht reichte,
wurde entschieden dann PD Nord ein kleines delay zu geben, damit es 1240 ns sind. 
(Es gab kein passendes Kabel um anzupassen) 

Danach haben wir alle andere Laufzeiten mit Gate&Delay daran angepasst.  
PD Nord: 1240 ns 
PD Süd: 1240 ns  
PMT Nord: 1240 ns (offset war 27 ns, extra delay ist 165,88 ns) 
PMT Mitte: 1240 ns (offset war 28 ns, extra delay ist 166,2 ns)   
XUV Anode: 1008 +/- 1 ns (nur bis zu CFD in Messhütte)  Delay muss noch angepasst werden! 

Date: 26.02.2025 @  18:35

E-cooler:  HV = 157366 +/- 1 V  (HV divider value)
E-cooler current = 200 mA (scale:  1V --> 10 mA) 

Schottky f_rev = 1.782012 +/- 1 MHz (measured value) 
f_b = 1.782013 MHz (set value) 

orbit length in ESR = 108.5 m (based on experience, injection is further out, not central) 

y = 1.30796 
ß = 0.64456 


We have 1 ion bunch in the ESR

Today, 25 FEB 2025 at 9:00 AM, our experiment was reviewed carefully by the safety committee. 
The experiment was accepted without problems. 
All was fine, only minor comments were made and only a few short-notice actions were required. 

The procedure has become much more complicated and lengthy over time, though. 
(Something to keep in mind.)

Many thanks to the whole team !!

Hochspannung Maßstabsfaktoren

-140 kV >>> 248514
-160 kV >>> 248515

According to Paul Indelicato

transition 3P1 -> 3P0  in 78Kr32+ : 

A	2.48E+08	1/s   "transition rate" 
t	4.03E-09	s     "lifetime 3P1" 
dv	3.95E+07	Hz    "natural line width" 
dE	1.63E-07	eV    "width in eV" 

Now, if we assume a final dp/p (after electron cooling) of the ion beam of ~1E-5, 
this corresponds to a longitudinal temperature of ~16000 K (~1.4 eV). 
This implies a Doppler width of ~26 GHz (ION frame). 

This is broader than the width of the laser pulse in the ION frame (between 4.4 and 23.4 GHz). 

This, in turn, implies that we should "see" the transition if we make 0.0024 nm steps in the UV (LAB frame). 
The transition would then be something like 2-3 steps wide. 

If we use this stepsize, and scan from 257.175 nm to 257.675 nm (LAB frame), we need 207 steps. 

If one step takes 1 minute (using 1 ESR cycle and fixed laser wavelength per cycle), one scan takes ~3.5 hours ! 
I think that is too long. 

For this procedure, the ESR cycle (injection -> next injection) must be faster. 
Also the time for the laser to change the wavelength must be fast, but that should be OK. 
We should try to get to sth. like 1 hour per scan. 

Berechnung der Frequenzbreiten des Lasers im Ionensystem 
Werte für die Frequezbreiten des Lasers aus Dissertation Benedikt Langfeld übernommen

v=0.644c 

Pulsdauer = 115ps
Frequenzbreite (FWHM) = 10.87GHz
Frequenzbreite Ionensystem = 23.36GHz

Pulsdauer = 240ps
Frequenzbreite (FWHM) = 4.19GHz
Frequenzbreite Ionensystem = 9.00GHz

Pulsdauer = 400ps
Frequenzbreite (FWHM) = 2.82GHz
Frequenzbreite Ionensystem = 6.06GHz

Pulsdauer = 735ps
Frequenzbreite (FWHM) = 2.05GHz
Frequenzbreite Ionensystem = 4.41GHz

Verkabelung von den Photodioden im ESR. Sind auch gelabelt.

PD gehen zuerst einmal in den FAMP (10x Verstärkung) 

PD NW -> ESR Panel 4 
PD SW -> ESR Panel 7 

XUV LED -> ESR Panel 8 

Erstes Bild ist das Strahlptofil in Höhe des Nord 
towers. 
Zweites Bild (mit Millimeterpapier) und Video zeigt 
das Strahlprofils etwa in Höhe des XUV Detektors im 
ESR. Das Zittern ist dabei durch anstoßen am Nord 
Tower entstanden, wichtig hier zu sehen ist das 
„Atmen“ des Strahlprofils, welches dabei allerdings 
örtlich fest bleibt. 

We had the chance to shortly enter the ESR, between 10:45 and 11:30. 

- We repositioned the PSDs of the TEM system. 
- We could see the laser beam at the ESR exit window. 
- We used a wedge at the exit window and directed the two laser beams onto a power meter and a fast photodiode. 
- We photographed the XUV detector setup. 
- We documented the cabling at the central cable panel. 

In the ESR laser lab we could see the laser beam power on the power meter and we could also see 
the laser pulses on the fast photodiode (scope). 

We still need a longer break (~2 hrs) to further optimize the setup and all the settings. 

Hitrap will kein ESR Zugang erlauben bevor 22 Uhr. Außerdem merken die, wenn ESR-SIS nicht laufen, dass sie morgens immer 1 Stunde Zeit verlieren weil nicht "angefordert" wurde. Deswegen wollen sie, dass ESR-SIS nachts auch weiter Strahl anfordern, etwa 1 mal pro 5 Minuten. Aber wir finden schon noch eine Lücke um reinzugehen.


Hitrap does not want to allow ESR access before 10 p.m. In addition, when ESR-SIS is not running, they notice that they always lose 1 hour of time in the morning because nothing was "requested". That's why they want ESR-SIS to continue requesting beams at night, about once every 5 minutes. But we can still find a gap to go in.

Volker Hannen kommt am 19.2 (Mittags) und dann machen wir Abends den XUV Detektor bereid.


Volker Hannen is coming on February 19th (in the afternoon) and then we'll get the XUV detector ready in the evening.

Es wird noch zwei 2 stündige Unterbrechungen am UNILAC geben. Wahrscheinlich diesen Freitag und nächste Woche Mittwoch oder Donnerstag. Am 25.2. wird dann die Gleitringdichtung der Pumpe am UNILAC gewechselt (8-18 Uhr) daher rechne ich mit Xe Strahl im ESR frühestes am 26.2.
Von HITRAP habe ich erfahren, dass wir Abends/Nachts was im Ring machen dürfen, ab 22 Uhr. z.B. am 17.2, 19.2 und 21.2.  Aber ich denke vorher (diese Woche) geht es bestimmt auch mal.

There will be two 2-hour breaks at the UNILAC. Probably this Friday and next week Wednesday or Thursday. On February 25th the mechanical seal of the pump on the UNILAC will be changed (8 a.m. to 6 p.m.) so I expect the Xe beam in the ESR on February 26th at the earliest.
I found out from HITRAP that we can do something in the ring in the evening/night, from 10 p.m. onwards. For example on February 17th, February 19th and February 21st.  But I think there will be some possibilities already this week.