Vibration Reduction in a Pulse Tube-Cooled High Purity Germanium Detector

Round 1

Reviewer 1 Report

The paper presents a low vibration portable pulse tube cryocooler (PTC) system for HPGe detector was manufactured.

The topic is interesting, and the manuscript is comprehensive. The results seem coherent and described with sufficient clarity. However, the novelty of the proposed technology is difficult to appreciate. The authors should describe what is the contribution and originality of this technology compared with other similar technologies. They simply state that 'Many technologies have been developed to reduce the degradation by reducing the cold stage vibration level by vibration isolators, reducing the vibration level of compressor by activate vibration control system, optimizing the digital filter technology in signal processing electronics associated with the detectors, using the low frequency rejector (LFR) filter removing most of the microphonic noise and so on.' For this, the authors must show some criticism on some of the existing technologies and to demonstrate the novelty and contribution of the proposed portable pulse tube cryocooler (PTC) system for HPGe detector.

It is necessary that the bibliography should be seriously improved. The paper is poorly documented. The literature survey is based only three references and these older than 8 years (please see Introduction). The rest of the references are not recent either. Reference 13 is the most recent, from 2019, but it is the only one.

Also, some issues should be reviewed before publication:

1. The abstract should be revised. Too many generalities are presented. Rather, the novelty of the paper should be highlighted here.
2. The conclusions should be presented in a concise form. Based on the results obtained some fundamental conclusions need to be drawn.
3. The text and English language in the paper must checked, edited, and corrected.

Author Response

Dear reviewer 

        According to your comments and suggestions, The following modifications have been made in this paper.

1. The abstract has been revised. The novelty of the paper has been highlighted. In this paper, the passive isolator can have same isolation performance when cooler is placed in any direction.
2. Some latest literatures about passive vibration reduction are added in the introduction. The authors show some criticism on some of the existing technologies.
3. The text and English language in the paper has been checked, edited, and corrected.

 Thank you for your rigorous comments.

Author Response File: Author Response.doc

Reviewer 2 Report

Thanks to the autors for their paper.

The issue of passive damper has been studied for many years. Authors should conduct a thorough search. They should compare the results of the search with their solution to show the novelty of their approach. I miss a more detailed description of the construction of the damper in the article. I also miss detailed explanation of vibration tests.

I have several comment to the article:

1. The red curve in Figure 8 seems very ideal to me. Was it really measured?
2. In Figure 2, the authors should add units to the vertical axis.
   
3. Figures 8 and 9 are confusing. They should be adjusted.
4. On the second page 2: "In this paper, a portable PTC HPGe detector is developed." So what is the main purpose of this paper?

Author Response

Dear Reviewer 

1. Some latest literatures about passive vibration reduction are added in the introduction. The authors show some criticism on some of the existing technologies.
2. Figure 8 has been retested. The magnification times of red curve data have some mistake.
3. Figure 2 no units to the vertical axis. According to the equation 1, the transmissibility is a dimensionless paraments and its unit is”1”.
4. Energy resolution is an important performance index for HPGe detector. Energy resolution degradation induced by the cooler is an important evaluation criterion for the HPGe electromechanically-cooled system. Figure 8 and figure 9 respectively show the energy resolution of the detector in the PTC switched-off and switched-on condition.

When the cooler switched-off, the effects of mechanical vibrations from the PTC is gone.

the effects induced by mechanical vibrations from PTC are produced.

4．” In this paper, a portable PTC HPGe detector is developed”. has been changed to “In this paper, a portable PTC ,suitable for HPGe detector, is developed.

    The main purpose of this paper is to introduced a portable PTC suitable for HPGe detector. An effective passive vibration isolation method is proposed for portable PTC. The vibration induced by the PTC undegraded the detector energy resolution.

Thank you for your rigorous comments.

Author Response File: Author Response.doc

Reviewer 3 Report

Abstract:
-"HPGe" I would suggest not to start with an abbrevation

Introduction:
- The abbravation HPGe should be introduced with High Purity Germanium before using
- "Firstly, A portable" should be "Firstly, a portable"

Section 2:
- Figure 1: Constants c and k, it should be able to read c an k from below or right (rules of technical drawing),
furthermore, waht ist the connection/difference between left and right part of figure 1?

Section 3:
- "The transmission of the vibration force ηis" blank missing between η and is... the same holds for all greak
symbols introduced below equation (2)
- Equation (1), F_max and F_0 not introduced
- Equation (2), what is k? stiffness, as introduced in Figure 1?
- An illustration of the phsyical model would be helpful to unterstand Equation (1) and (2)
- "Three" or "The"?
- Fiugre.2... blank missing
- "The figures indicates that the transmissibility is 7% in the main frequency 64Hz and
have lower transmissibility at harmonic frequency." is the sentence well fumulated. I would like to 
suggest to chek language...
- Table 2: all components are assumed to be linear, time-invariant and constant in temerature?
- Figure 2: Transmissibility according to Equation (1)? Damping raio 1.3? I guess 1.3% or 0.013. Am I right?
Furthermore, what is the fall-off rate, if the transmissibility is plotted in a logarithmic scale?

Section 4 and section 5 are verry short. Is it possible to reduce the numer of sections in the orginization
of the paper?

Section 5:
- Why the force sensor (Kistler 9257B) is specified in detail, but the "A PCB three-dimension" not? 

Section 6:
- "64Hz ,50W AC. The" bettercorrect the position of the blank "64Hz, 50W AC. The"
- "Table.2" why not "Table 2"?
- Figure 4 and 5: it is difficuld/or not possible to identify all green bars. For example it is nor clear, if
a green bar exists at 700Hz in the third row of figure 4. A logarithmic scale could help at this point...

Section 7:
- again Figure.6 why again Figure_Point_Number? Also Figure.7...
- "Table3" blank missing...
- "The ratios of detector mounting interface arms to cold tip arms" two times arms?
- "10mins" what is the unit "mins", it is unkown to me...
- Figure 6: as Figure 4 and 5, black bares difficult to identify... this works against interpretation of data
- Figure.7... Figure.8... why the POINT again...
- Unit "keV" need to be introduced/explained
- Figure 7... it is impossible to interprete the red line. Again, a logarithmic measure could help...
- Figure 8 and 9... quality of data label should be improved / difficult to read...

Section 8:
- What is the meaning of "high frequency"? high compared to wave length and dimension of test object?

Author Response

Dear reviewer

Abstract: It has been modified according to the suggestion.

Introduction: It has been modified according to the suggestion.

Section 2

Figure 1. Left part of figure1 is mechanical dynamics schematic diagram of CVIK and right part of figure1 is the structure schematic diagram of CVIK.

In the Figure 1, Four spring isolators are evenly distributed along the compressor circumference direction. The constants c and k, it should be able to read in a counterclockwise direction.

Section 3:

1., , k, λ were introduced.

2.The physical model of linear single degree freedom spring and damper system was complemented.

3.Table 2: all components are assumed to be linear, time-invariant and constant in temperature.

4.The damping ratio provides a mathematical means of expressing the level of damping in a system relative to critical damping. The damping ratio 1.3 is the spring isolator structure parameters. The damping ratio is not the transmissibility.

 

5.The transmissibility is the “fall-off rate”. According to equation 1, the transmissibility can be calculated in different frequency ratio (λ). The natural frequency of CVIK is assumed to be 13Hz. Fiugre.2 shows the transmissibility of the CVIK at different vibrational frequencies.

Section 4 and section 5

In the original manuscript, Section 3 and section 4 is the design of PTC passive vibration isolation which contain compressor isolation system and detector interface anti-vibration. Section 6 and section 7 are section 5 child sections. The editor cut the child sections. Reducing the number of sections in the organization of the paper can be performed.

 

Section5

The acceleration sensor model has been replenished.

Section6

It has been modified according to the suggestion.

Section 7

Figure5,6,8,9,10 have been modified.

The unit of a_rms is rms （root-mean-square）.

Section 8

“The high frequency” is the meaning of vibration harmonic frequency.

 Thank you for your rigorous comments.

Author Response File: Author Response.doc

Round 2

Reviewer 1 Report

The authors have answered all issues. The additions are sufficient, and the manuscript has been improved. Therefore, I think the paper is worth to be published in Applied Sciences.

Reviewer 2 Report

I have no other suggestions. Thank you.