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| Technical specification |
| --- |
| public procurement entitled |
|  |
| „UPOL/FoS/DEP - Cryostat systems for Mössbauer spectroscopy“ |
|  |
|  |
|  |

Description of the Subject‑Matter of the Public procurement

**1. Cryogen-free cryostat – side-sample loading vacuum chamber design**

*The ultra-low vibration closed cycle cryostat system designed for Mössbauer spectroscopy, configured for reflection and transmission geometry.*

1.1. General Requirements:

1. Closed-cycle cryogen-free cryostat.
2. The vibration velocity on the platform of the sample chamber or of a sample mounted on the sample holder inside the cryostat chamber, relative to the optical table, shall not exceed 0.03 mm/s in the minimum frequency range 1 Hz - 2 kHz across the full operating temperature range.
   1. Compliance with this requirement may be demonstrated by providing a Mössbauer measurement report showing the effect of mechanical vibrations on the spectral line width of the calibration sample, again with a maximum broadening of 0.03 mm/s.
   2. This requirement is intended to prevent excessive line broadening in the Mössbauer spectrum; for an alpha-iron calibration sample (six spectral lines), the linewidth in the absence of vibration should be approximately 0.28 mm/s.
3. Cryocooler base temperature ≤ 4.2 K measured without heat loads.
4. Temperature range from base temperature to ≥ 300 K.
5. Temperature stability ≤ 100 mK (for T ≤ 10 K).
6. Cool-down time to 5 K ≤ 5 hours.
7. Minimum one instrumentation feedthrough port for ≥ 5-Pin connector for in-situ sample research.
8. Temperature control system, external or built-in, programmable, with remote (SW, USB, and/or Ethernet) access.

1.2. Measurement Design:

1. Side-mounted measurement chamber.
2. Sample insertion via removal of the upper chamber cover.
3. Sample maintained under high vacuum during the measurement.
4. Measurement access ports in multiple configurations via ≥ 4 windows.
5. Transmission Mössbauer geometry with opposing windows.
6. Reflection Mössbauer geometry with ≥ 2 windows perpendicular to each other.
7. Inner heat and/or radiation shield.
8. Sample holder included for transmission geometry.
9. Sample holder temperature ≤ 5 K measured without heat loads and with closed window ports.
10. Diameter of the apertures in the gamma beam path ≥ 8 mm.
11. All windows in the gamma beam path must be made exclusively of Kapton or Mylar with effective thickness optimum for 14.4 keV gamma photons penetration.
12. No other materials permitted in the direct beam path.

1.3. Compressor and Infrastructure:

1. Helium compressor, required water-cooled.
2. Power supply up to 3x400V/32A/5P 50 Hz, or up to 230V/32A/3P 50 Hz.
3. High-pressure helium supply and return hoses ≥ 10 m long each.
4. Oil-free high vacuum system required for continuous and independent operation.

1.4. Vibration Requirement:

1. Anti-vibration solution must be included (dedicated vibration isolation stand/table or integrated isolation system).
2. Vibrational level must be stated – amplitude and frequency characteristics.
3. Documented vibration measurement data required for stated vibrational level.

**2. Cryogen-Free Cryostat – Top-sample loading helium vapor design**

*The ultra-low vibration closed cycle cryostat system designed for Mössbauer spectroscopy, configured for transmission geometry with top loading sample in helium exchange gas.*

2.1. General Requirements:

1. Closed-cycle cryogen-free cryostat.
2. The vibration velocity of a sample mounted on the sample holder inside the cryostat chamber, relative to the laboratory reference frame, shall not exceed 0.03 mm/s over the minimum frequency range 1 Hz – 2 kHz across the full operating temperature range.
   1. Compliance with this requirement may be demonstrated by providing a Mössbauer measurement report showing the effect of mechanical vibrations on the spectral line width of the calibration sample, again with a maximum broadening of 0.03 mm/s.
   2. This requirement is intended to prevent excessive line broadening in the Mössbauer spectrum; for an alpha-iron calibration sample (six spectral lines), the linewidth in the absence of vibration should be approximately 0.28 mm/s.
3. Cryocooler base temperature ≤ 4.2 K measured without heat loads.
4. Temperature range from base temperature to ≥ 300 K.
5. Temperature stability ≤ 100 mK (for T ≤ 10 K).
6. Cool-down time to 5 K ≤ 4 hours.
7. Minimum one instrumentation feedthrough port for ≥ 5-Pin connector for in-situ sample research.
8. Temperature control system, external or built-in, programmable, with remote (SW, USB, and/or Ethernet) access.

2.2. Measurement Design:

1. Top-loading sample configuration via vertical sample rod.
2. Sample positioned in helium vapor (exchange gas) environment during measurement.
3. Capability to insert a pre-cooled sample.
4. Measurement access ports in transmission configurations via ≥ 2 windows.
5. Transmission Mössbauer geometry with opposing windows.
6. Sample holder included for transmission geometry.
7. Sample holder temperature ≤ 5 K measured without heat loads and with closed window ports.
8. Sample holder with rotation motion.
9. Diameter of the apertures in the gamma beam path ≥ 8 mm.
10. All windows in the gamma beam path must be made exclusively of Kapton or Mylar with effective thickness optimum for 14.4 keV gamma photons penetration.
11. No other materials permitted in the direct beam path.

2.3. Compressor and Infrastructure:

1. Helium compressor, required water-cooled.
2. Power supply up to 3x400V/32A/5P 50 Hz, or up to 230V/32A/3P 50 Hz
3. High-pressure helium supply and return hoses ≥ 10 m long each.
4. Oil-free high vacuum system required for continuous and independent operation.

2.4. Vibration Requirement:

1. Anti-vibration solution must be included (dedicated vibration isolation stand/table or integrated isolation system).
2. Vibrational level must be stated – amplitude and frequency characteristics.
3. Documented vibration measurement data required for stated vibrational level.

**3. Shared water-cooling system with external/outdoor heat exchanger**

*The cooling system must serve at minimum three helium compressors.*

3.1. Cooling Requirements:

1. Closed-loop chilled water system, air cooled.
2. Cooling power ≥ 10 kW.
3. Continuous 24/7 operation capability.
4. Adjustable outlet temperature in the minimum range: 15–25 °C.
5. Installation of hydraulic branches for each compressor.
6. Instrumentation for individual and/or simultaneous full-load operation of connected helium compressors.
7. External Heat Exchanger – outdoor installation.

3.2. Installation Scope included in the tender:

1. Chilled water unit (split or monoblock acceptable).
2. Insulated piping (length optimized based on the on-site conditions).
3. Hydraulic fittings and isolation valves.
4. Electrical connections.
5. Commissioning and full-load testing with minimum three compressors (point 1.3., point 2.3. and already installed compressor in the laboratory with required cooling capacity 4 kW).

3.3. Technical Documentation:

1. Complete technical documentation must be included in the tender to allow installation site preparation.
2. Dimensional and layout drawings.
3. Foundation requirements for external installation.
4. Weather protection or shelter requirements.
5. Internal wall penetrations and routing paths.
6. Electrical and hydraulic utility requirements.

Page 1

| Technical specification                                           |
| ----------------------------------------------------------------- |
| public procurement entitled                                       |
|                                                                   |
| „UPOL/FoS/DEP - Cryostat systems for Mössbauer spectroscopy“      |
|                                                                   |
|                                                                   |
|                                                                   |

Description of the Subject‑Matter of the Public procurement

**1. Cryogen-free cryostat – side-sample loading vacuum chamber design**

*The ultra-low vibration closed cycle cryostat system designed for Mössbauer spectroscopy, configured for reflection and transmission geometry.*

1.1. General Requirements:

  1. Closed-cycle cryogen-free cryostat.
  2. The vibration velocity on the platform of the sample chamber or of a sample mounted on the sample holder inside the cryostat chamber, relative to the optical table, shall not exceed 0.03 mm/s in the minimum frequency range 1 Hz - 2 kHz across the full operating temperature range.
    1. Compliance with this requirement may be demonstrated by providing a Mössbauer measurement report showing the effect of mechanical vibrations on the spectral line width of the calibration sample, again with a maximum broadening of 0.03 mm/s.
    2. This requirement is intended to prevent excessive line broadening in the Mössbauer spectrum; for an alpha-iron calibration sample (six spectral lines), the linewidth in the absence of vibration should be approximately 0.28 mm/s.
  3. Cryocooler base temperature ≤ 4.2 K measured without heat loads.
  4. Temperature range from base temperature to ≥ 300 K.
  5. Temperature stability ≤ 100 mK (for T ≤ 10 K).
  6. Cool-down time to 5 K ≤ 5 hours.
  7. Minimum one instrumentation feedthrough port for ≥ 5-Pin connector for in-situ sample research.
  8. Temperature control system, external or built-in, programmable, with remote (SW, USB, and/or Ethernet) access.

1.2. Measurement Design:

  1. Side-mounted measurement chamber.
  2. Sample insertion via removal of the upper chamber cover.

Page 2

3. Sample maintained under high vacuum during the measurement.
  4. Measurement access ports in multiple configurations via ≥ 4 windows.
  5. Transmission Mössbauer geometry with opposing windows.
  6. Reflection Mössbauer geometry with ≥ 2 windows perpendicular to each other.
  7. Inner heat and/or radiation shield.
  8. Sample holder included for transmission geometry.
  9. Sample holder temperature ≤ 5 K measured without heat loads and with closed window ports.
  10. Diameter of the apertures in the gamma beam path ≥ 8 mm.
  11. All windows in the gamma beam path must be made exclusively of Kapton or Mylar with effective thickness optimum for 14.4 keV gamma photons penetration.
  12. No other materials permitted in the direct beam path.

1.3. Compressor and Infrastructure:

  1. Helium compressor, required water-cooled.
  2. Power supply up to 3x400V/32A/5P 50 Hz, or up to 230V/32A/3P 50 Hz.
  3. High-pressure helium supply and return hoses ≥ 10 m long each.
  4. Oil-free high vacuum system required for continuous and independent operation.

1.4. Vibration Requirement:

  1. Anti-vibration solution must be included (dedicated vibration isolation stand/table or integrated isolation system).
  2. Vibrational level must be stated – amplitude and frequency characteristics.
  3. Documented vibration measurement data required for stated vibrational level.

**2. Cryogen-Free Cryostat – Top-sample loading helium vapor design**

*The ultra-low vibration closed cycle cryostat system designed for Mössbauer spectroscopy, configured for transmission geometry with top loading sample in helium exchange gas.*

2.1. General Requirements:

  1. Closed-cycle cryogen-free cryostat.
  2. The vibration velocity of a sample mounted on the sample holder inside the cryostat chamber, relative to the laboratory reference frame, shall not exceed 0.03 mm/s over the minimum frequency range 1 Hz – 2 kHz across the full operating temperature range.
    1. Compliance with this requirement may be demonstrated by providing a Mössbauer measurement report showing the effect of mechanical vibrations on the spectral line width of the calibration sample, again with a maximum broadening of 0.03 mm/s.
    2. This requirement is intended to prevent excessive line broadening in the Mössbauer spectrum; for an alpha-iron calibration sample (six spectral lines), the linewidth in the absence of vibration should be approximately 0.28 mm/s.
  3. Cryocooler base temperature ≤ 4.2 K measured without heat loads.
  4. Temperature range from base temperature to ≥ 300 K.
  5. Temperature stability ≤ 100 mK (for T ≤ 10 K).
  6. Cool-down time to 5 K ≤ 4 hours.
  7. Minimum one instrumentation feedthrough port for ≥ 5-Pin connector for in-situ sample research.
  8. Temperature control system, external or built-in, programmable, with remote (SW, USB, and/or Ethernet) access.

2.2. Measurement Design:

Page 3

1. Top-loading sample configuration via vertical sample rod.
  2. Sample positioned in helium vapor (exchange gas) environment during measurement.
  3. Capability to insert a pre-cooled sample.
  4. Measurement access ports in transmission configurations via ≥ 2 windows.
  5. Transmission Mössbauer geometry with opposing windows.
  6. Sample holder included for transmission geometry.
  7. Sample holder temperature ≤ 5 K measured without heat loads and with closed window ports.
  8. Sample holder with rotation motion.
  9. Diameter of the apertures in the gamma beam path ≥ 8 mm.
  10. All windows in the gamma beam path must be made exclusively of Kapton or Mylar with effective thickness optimum for 14.4 keV gamma photons penetration.
  11. No other materials permitted in the direct beam path.

2.3. Compressor and Infrastructure:

  1. Helium compressor, required water-cooled.
  2. Power supply up to 3x400V/32A/5P 50 Hz, or up to 230V/32A/3P 50 Hz
  3. High-pressure helium supply and return hoses ≥ 10 m long each.
  4. Oil-free high vacuum system required for continuous and independent operation.

2.4. Vibration Requirement:

  1. Anti-vibration solution must be included (dedicated vibration isolation stand/table or integrated isolation system).
  2. Vibrational level must be stated – amplitude and frequency characteristics.
  3. Documented vibration measurement data required for stated vibrational level.

**3. Shared water-cooling system with external/outdoor heat exchanger**

*The cooling system must serve at minimum three helium compressors.*

3.1. Cooling Requirements:

  1. Closed-loop chilled water system, air cooled.
  2. Cooling power ≥ 10 kW.
  3. Continuous 24/7 operation capability.
  4. Adjustable outlet temperature in the minimum range: 15–25 °C.
  5. Installation of hydraulic branches for each compressor.
  6. Instrumentation for individual and/or simultaneous full-load operation of connected helium compressors.
  7. External Heat Exchanger – outdoor installation.

3.2. Installation Scope included in the tender:

  1. Chilled water unit (split or monoblock acceptable).
  2. Insulated piping (length optimized based on the on-site conditions).
  3. Hydraulic fittings and isolation valves.
  4. Electrical connections.
  5. Commissioning and full-load testing with minimum three compressors (point 1.3., point 2.3. and already installed compressor in the laboratory with required cooling capacity 4 kW).

3.3. Technical Documentation:

  1. Complete technical documentation must be included in the tender to allow installation site preparation.

Page 4

2. Dimensional and layout drawings.
  3. Foundation requirements for external installation.
  4. Weather protection or shelter requirements.
  5. Internal wall penetrations and routing paths.
  6. Electrical and hydraulic utility requirements.