Home page of Fred Hartjes

Last update December 12, 2014


Sant'Agostino, San Gimignano (Italy), June 2010


My present life as a retired person

May 2010, the two years extension of my FOM contract at Nikhef has been ended, so I could have really started enjoying the retirement state. However, three workshops: Freiburg, Bari and CERN, a conference IPRD10, the Gossip testbeam at CERN (SPS), and the completion of two spark chamber set-ups (Nikhef and NEMO) have kept me busy till the end of 2010.

At my formal “afscheid” on January 27, 2011, Nikhef's director Frank Linde referred to the diamond on the invitation card, suggesting that I should continue my presence at Nikhef until my diamond anniversary, i.e. September 2026.  Although I can still been seen at Nikhef for most of the working days, I cannot guarantee that I will make this.

For the rest live is easy and enjoyable now as a recently retired person with good health, giving me peace for things like belles-lettres, Anker stones and mending my gardens in de Kwakel and at my holiday home in Koekange, altogether with my dear wife Josephine.

Subjects I am still involved in at Nikhef

As member of the Nikhef R&D group, I contribute to:

  • Development of Gossip and GridPix detectors for upgrade of ATLAS Inner Detector at the sLHC. These detectors consist of a pixel chip, presently 256 x 256 cells of 55 x 55 µm pitch, an amplification grid at 50 µm height, and a drift volume. For Gossip, the drift volume is only 1 mm high. The functioning of Gossip is described in the backup document (4.8 Mb) for the review of the Upgrade Steering group. Experimental results are presented and discussed at the RD51 collaboration exploring micropattern gas detectors.
    • ageing and rate effects
    • position resolution
    • optimising the gas mixture
  • Spark chambers to demonstrate cosmic rays (click here for engineering drawings)
  • Testing and evaluating the MiniHV high voltage power supply intended for micropattern gas detectors. This power supply, recently developed by Nikhef's electronic department, is dedicated to micropattern gas detectors


Talks (only the most relevant) for downloading

Some pictures of "Studenten Societeit Olofspoort" (pdf, 5.8 Mb)

Mechanical construction of Gossip/GridPix. At certain distance (1 mm or more) above the amplification grid a cathode plane is positioned.

Functioning of Gossip

A charged elementary particle traverses the detector, leaving a track of electron-ion pairs in the detector gas. Subsequently, the lionization electrons drift towards the amplification grid and are collected by one of the holes. Gas amplification (~5000) takes place in the high electrical field between amplification grid and the pixel chip. The primary electron is detected in 3 coordinates: X and Y as the address of the hit pixel cell, Z as the arrival time of the charge signal on the pixel chip.
























Anker stones

Go to Anker page



Hunting castle DS 9


English castle DS 33 during construction (design never published by Richter)